From eb62fc6c4c21fa4436dcf1283daa2be4e34d6f6f Mon Sep 17 00:00:00 2001
From: Matthias Nott <mnott@mnsoft.org>
Date: Sun, 12 Apr 2026 20:53:21 +0200
Subject: [PATCH] # Add source references to German Air Law exam questions

---
 SPL Exam Questions EN/50 - Meteorology.md | 1181 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 1,176 insertions(+), 5 deletions(-)

diff --git a/SPL Exam Questions EN/50 - Meteorology.md b/SPL Exam Questions EN/50 - Meteorology.md
index 94cb6c7..e124403 100644
--- a/SPL Exam Questions EN/50 - Meteorology.md
+++ b/SPL Exam Questions EN/50 - Meteorology.md
@@ -22,6 +22,10 @@
 #### Key Terms
 
 CB = Cumulonimbus (thunderstorm cloud)
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+#### Source
+
+- [?] Source non identifiée
 ### Q2: What type of fog forms when humid and nearly saturated air is forced to rise along the slopes of hills or shallow mountains by the prevailing wind? ^t50q2
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q2) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q2)
@@ -38,6 +42,12 @@
 #### Explanation
 
 Orographic fog forms when wind-driven humid air is mechanically lifted along a slope, cooling adiabatically until it reaches the dew point. Radiation fog requires calm nights with radiative ground cooling, advection fog forms when warm moist air moves over a cold surface, and steaming fog (Arctic sea smoke) occurs when cold air passes over warm water — none of these involve slope-forced lifting.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q12 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.21)
+- [QuizVDS Q2](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q2): Answer D
 
 ### Q3: What phenomenon is known as "blue thermals"? ^t50q3
 
@@ -56,6 +66,10 @@
 
 "Blue thermals" exist when the lifting condensation level (LCL) is very high — the air is too dry to reach its dew point before the thermal tops out. As a result, thermals rise but no cumulus clouds form, leaving the sky clear ("blue"). For glider pilots this is challenging since there are no visual cloud markers to indicate thermal location, and the cloudbase is beyond the thermal ceiling.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q4: The expression "beginning of thermals" refers to the moment when thermal intensity ^t50q4
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q4) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q4)
@@ -77,6 +91,10 @@
 
 - **AGL** = Above Ground Level
 - **MSL** = Mean Sea Level
+
+#### Source
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+- [?] Source non identifiée
 ### Q5: The "trigger temperature" is the temperature that ^t50q5
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q5) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q5)
@@ -94,6 +112,10 @@
 
 The trigger temperature is the minimum surface temperature that must be reached before thermals can rise to the condensation level and form cumulus clouds. It is derived from the aerological diagram (tephigram/Stüve diagram) by tracing the dry adiabatic lapse rate from the morning sounding's moisture level back to the surface. Until this temperature is reached, thermals may exist but will not produce cumulus markers.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q6: What is meant by "over-development" in a weather report? ^t50q6
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q6) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q6)
@@ -111,6 +133,10 @@
 
 Over-development occurs when cumulus clouds continue growing vertically beyond the thermal inversion or become self-sustaining through latent heat release, developing into cumulonimbus (Cb) with heavy rain showers, lightning, and hail. This typically happens during humid summer afternoons when atmospheric instability is high and the inhibiting layer is weak. For glider pilots, over-development signals the end of safe soaring conditions and a need to land.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q7: The gliding weather report indicates environmental instability. Morning dew is present on the grass and no thermals are currently active. What thermal development can be expected? ^t50q7
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q7) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q7)
@@ -128,6 +154,10 @@
 
 Morning dew indicates the air cooled to the dew point overnight (radiation cooling), but this is temporary. Once solar insolation heats the ground, the surface temperature rises, warming the air above it until the temperature exceeds the trigger temperature. Environmental instability means the lapse rate is steep enough to sustain thermals once they begin, so good thermal conditions are likely to develop during the morning hours.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q8: What effect on thermal activity can be expected when cirrus clouds approach from one direction and become increasingly dense, blocking the sun? ^t50q8
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q8) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q8)
@@ -145,6 +175,10 @@
 
 Thermals are driven by differential heating of the ground by solar radiation. Thickening cirrus clouds progressively filter out solar energy, reducing ground heating and therefore thermal strength and depth. Dense cirrus can reduce insolation enough to stop thermal activity entirely. Additionally, approaching cirrus from one direction often indicates an advancing warm front, which brings widespread cloud, stable conditions, and further suppression of thermals.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q9: What situation is known as "shielding"? ^t50q9
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q9) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q9)
@@ -162,6 +196,10 @@
 
 Shielding describes the effect of high or medium cloud layers (cirrus, cirrostratus, altostratus) that block solar radiation and suppress thermal development below. Even partial cloud cover at these levels can significantly reduce ground insolation. Gliding forecasts include shielding assessments to indicate when and where thermals will be weakened or absent due to cloud cover above the expected thermal layer.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q10: While planning a 500 km triangle flight, there is a squall line 100 km west of the departure airfield, extending north to south and moving east. What would be a sensible decision regarding the weather? ^t50q10
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q10) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q10)
@@ -179,6 +217,10 @@
 
 A squall line is an organized line of severe thunderstorms that is notoriously fast-moving, unpredictable, and extremely dangerous. Moving at typical speeds of 30–60 km/h, a squall line 100 km away could reach the airfield within 2–3 hours. Flying below Cb cloud bases or attempting to navigate between cells exposes the glider to extreme turbulence, windshear, hail, and downdrafts. The only safe option is to not fly until the hazard has completely passed.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q11: What is the gas composition of "air"? ^t50q11
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q11) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q11)
@@ -196,6 +238,13 @@
 
 Dry air by volume is approximately 78% nitrogen (N2), 21% oxygen (O2), and the remaining 1% consists of argon, carbon dioxide, and other trace gases. Water vapour is variable (0–4%) and is not counted in the standard dry-air composition. Knowing air composition is fundamental to understanding atmospheric physics, density calculations, and the behaviour of aircraft engines and instruments.
 
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+#### Source
+
+- Examen Blanc: [VV Q8 p.108](Questionnaire%20toutes%20branches%20VV.pdf#page=108) (score: 0.44)
+- [QuizVDS Q11](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q11): Answer B
+- PDF Answer: D
+
 ### Q12: In which atmospheric layer are weather phenomena predominantly found? ^t50q12
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q12) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q12)
@@ -212,6 +261,13 @@
 #### Explanation
 
 The troposphere extends from the surface to approximately 8–16 km depending on latitude and season. It contains approximately 75–80% of the atmosphere's total mass and almost all its water vapour. Convection, cloud formation, precipitation, fronts, and wind phenomena all occur here because temperature decreases with height, driving convective instability. Above the tropopause, the stratosphere is stable and largely cloud-free.
+
+
+#### Source
+
+- Examen Blanc: [VV Q6 p.108](Questionnaire%20toutes%20branches%20VV.pdf#page=108) (score: 0.22)
+- [QuizVDS Q12](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q12): Answer D
+- PDF Answer: B
 
 ### Q13: What is the mass of a "cube of air" with 1 m edges at MSL according to ISA? ^t50q13
 
@@ -234,6 +290,10 @@
 
 - **ISA** = International Standard Atmosphere
 - **MSL** = Mean Sea Level
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+#### Source
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+- [?] Source non identifiée
 ### Q14: At what rate does the temperature change with increasing altitude according to ISA within the troposphere? ^t50q14
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q14) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q14)
@@ -254,6 +314,13 @@
 #### Key Terms
 
 ISA = International Standard Atmosphere
+
+#### Source
+
+- Examen Blanc: [VV Q30 p.113](Questionnaire%20toutes%20branches%20VV.pdf#page=113) (score: 0.28)
+- [QuizVDS Q14](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q14): Answer A
+- PDF Answer: D
+
 ### Q15: What is the mean tropopause height according to the ISA (ICAO Standard Atmosphere)? ^t50q15
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q15) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q15)
@@ -275,6 +342,13 @@
 
 - **ISA** = International Standard Atmosphere
 - **ICAO** = International Civil Aviation Organization
+
+#### Source
+
+- Examen Blanc: [VV Q7 p.108](Questionnaire%20toutes%20branches%20VV.pdf#page=108) (score: 0.23)
+- [QuizVDS Q15](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q15): Answer B
+- PDF Answer: D
+
 ### Q16: The "tropopause" is defined as ^t50q16
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q16) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q16)
@@ -292,6 +366,10 @@
 
 The tropopause is the transition boundary between the troposphere (where temperature decreases with height) and the stratosphere (where temperature initially remains constant then increases due to ozone absorption of UV radiation). It acts as a "lid" on convection — cumulonimbus clouds that reach it spread out laterally to form the characteristic anvil shape. Jet streams are located near the tropopause.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q17: In which unit are temperatures reported by European meteorological aviation services? ^t50q17
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q17) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q17)
@@ -312,6 +390,10 @@
 #### Key Terms
 
 ICAO = International Civil Aviation Organization
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+#### Source
+
+- [?] Source non identifiée
 ### Q18: What is meant by an "inversion layer"? ^t50q18
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q18) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q18)
@@ -329,6 +411,13 @@
 
 An inversion "inverts" the normal lapse rate — instead of temperature falling with height, it rises. This creates a very stable layer that acts as a lid on convection, trapping thermals below it, concentrating pollutants, and promoting fog and low cloud formation beneath it. For glider pilots, a low-level inversion caps thermal height; a subsidence inversion in a high-pressure system limits soaring altitude and is often associated with haze.
 
+
+#### Source
+
+- Examen Blanc: [VV Q30 p.113](Questionnaire%20toutes%20branches%20VV.pdf#page=113) (score: 0.27)
+- [QuizVDS Q18](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q18): Answer A
+- PDF Answer: D
+
 ### Q19: What is meant by an "isothermal layer"? ^t50q19
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q19) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q19)
@@ -345,6 +434,13 @@
 #### Explanation
 
 An isothermal layer maintains constant temperature with increasing altitude. Like an inversion, it is more stable than the standard atmosphere and inhibits convection. The lower stratosphere exhibits an isothermal region immediately above the tropopause. Isothermal layers can also occur in the troposphere and, like inversions, act as a cap on thermal development and cloud growth.
+
+
+#### Source
+
+- Examen Blanc: [VV Q30 p.113](Questionnaire%20toutes%20branches%20VV.pdf#page=113) (score: 0.27)
+- [QuizVDS Q19](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q19): Answer B
+- PDF Answer: D
 
 ### Q20: The temperature lapse rate with increasing altitude within the troposphere according to ISA is ^t50q20
 
@@ -366,6 +462,12 @@
 #### Key Terms
 
 ISA = International Standard Atmosphere
+
+#### Source
+
+- Examen Blanc: [S1S Q1 p.40](Exa%20Blanc%20Série_1_Specifiques.pdf#page=40) (score: 0.23)
+- [QuizVDS Q20](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q20): Answer C
+
 ### Q21: Which process may produce an inversion layer at around 5000 ft (1500 m) altitude? ^t50q21
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q21) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q21)
@@ -383,6 +485,10 @@
 
 Subsidence inversion forms when air in the centre of a high-pressure area sinks over a wide area. As the air descends, it warms adiabatically, but because the lower air has not warmed at the same rate, the descending layer becomes warmer than the air below it — creating an inversion, typically around 1500–3000 m. This is characteristic of anticyclonic conditions: stable weather, limited convection, and haze or smog trapped below the inversion.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q22: A ground-level inversion can be caused by ^t50q22
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q22) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q22)
@@ -400,6 +506,10 @@
 
 Radiation inversion forms on calm, clear nights when the ground radiates heat into space and cools rapidly. The air in contact with the ground also cools, while air a few hundred metres above remains warmer — creating a temperature inversion near the surface. This type of inversion is common in anticyclonic conditions and often produces radiation fog or low stratus in the morning, which burns off as the sun heats the ground.
 
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+- [?] Source non identifiée
 ### Q23: What is the ISA standard pressure at FL 180 (5500 m)? ^t50q23
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q23) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q23)
@@ -421,6 +531,13 @@
 
 - **FL** = Flight Level
 - **ISA** = International Standard Atmosphere
+
+#### Source
+
+- Examen Blanc: [VV Q15 p.110](Questionnaire%20toutes%20branches%20VV.pdf#page=110) (score: 0.27)
+- [QuizVDS Q23](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q23): Answer D
+- PDF Answer: D
+
 ### Q24: Which processes lead to decreasing air density? ^t50q24
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q24) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q24)
@@ -437,6 +554,13 @@
 #### Explanation
 
 Air density is governed by the ideal gas law: density = pressure / (specific gas constant × temperature). Density decreases when pressure decreases (fewer molecules per unit volume) or when temperature increases (molecules move faster and spread apart). Both increasing temperature AND decreasing pressure simultaneously reduce density most effectively. This is why density altitude (the altitude equivalent of the actual air density) matters for aircraft performance on hot, high-altitude airfields.
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+#### Source
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+- Examen Blanc: [VV Q139 p.240](Questionnaire%20toutes%20branches%20VV.pdf#page=240) (score: 0.25)
+- [QuizVDS Q24](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q24): Answer C
+- PDF Answer: B
 
 ### Q25: The pressure at MSL under ISA conditions is ^t50q25
 
@@ -462,6 +586,13 @@
 - **ICAO** = International Civil Aviation Organization
 - **MSL** = Mean Sea Level
 - **QNE** = Standard pressure setting (1013.25 hPa)
+
+#### Source
+
+- Examen Blanc: [VV Q15 p.110](Questionnaire%20toutes%20branches%20VV.pdf#page=110) (score: 0.21)
+- [QuizVDS Q25](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q25): Answer A
+- PDF Answer: D
+
 ### Q26: At what height is the ISA tropopause located? ^t50q26
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q26) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q26)
@@ -482,6 +613,10 @@
 #### Key Terms
 
 ISA = International Standard Atmosphere
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+#### Source
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+- [?] Source non identifiée
 ### Q27: The barometric altimeter shows height above ^t50q27
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q27) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q27)
@@ -505,6 +640,13 @@
 - **QNH** = Pressure adjusted to mean sea level
 - **QFE** = Atmospheric pressure at aerodrome elevation
 - **QNE** = Standard pressure setting (1013.25 hPa)
+
+#### Source
+
+- Examen Blanc: [VV Q15 p.110](Questionnaire%20toutes%20branches%20VV.pdf#page=110) (score: 0.41)
+- [QuizVDS Q27](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q27): Answer B
+- PDF Answer: D
+
 ### Q28: The altimeter can be checked on the ground by setting ^t50q28
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q28) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q28)
@@ -529,6 +671,13 @@
 - **AIP** = Aeronautical Information Publication
 - **MSL** = Mean Sea Level
 - **QNE** = Standard pressure setting (1013.25 hPa)
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+#### Source
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+- Examen Blanc: [VV Q20 p.111](Questionnaire%20toutes%20branches%20VV.pdf#page=111) (score: 0.22)
+- [QuizVDS Q28](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q28): Answer C
+- PDF Answer: C
+
 ### Q29: With QFE set, the barometric altimeter indicates ^t50q29
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q29) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q29)
@@ -551,6 +700,13 @@
 - **QFE** = Atmospheric pressure at aerodrome elevation
 - **AGL** = Above Ground Level
 - **MSL** = Mean Sea Level
+
+#### Source
+
+- Examen Blanc: [VV Q77 p.162](Questionnaire%20toutes%20branches%20VV.pdf#page=162) (score: 0.38)
+- [QuizVDS Q29](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q29): Answer B
+- PDF Answer: A
+
 ### Q30: With QNH set, the barometric altimeter indicates ^t50q30
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q30) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q30)
@@ -579,6 +735,13 @@
 - **QFE** = Atmospheric pressure at aerodrome elevation
 - **ISA** = International Standard Atmosphere
 - **MSL** = Mean Sea Level
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+#### Source
+
+- Examen Blanc: [VV Q77 p.162](Questionnaire%20toutes%20branches%20VV.pdf#page=162) (score: 0.43)
+- [QuizVDS Q30](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q30): Answer B
+- PDF Answer: A
+
 ### Q31: How can wind speed and direction be determined from surface weather charts? ^t50q31
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q31) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q31)
@@ -609,6 +772,10 @@
 - **Hypsometric lines** = contour lines of geopotential height on upper-air charts (not surface charts)
 - **Friction layer** = lowest ~600-1000 m of the atmosphere where surface drag affects wind
 
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+- [?] Source non identifiée
 ### Q32: Which force is responsible for causing "wind"? ^t50q32
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q32) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q32)
@@ -626,6 +793,10 @@
 
 Wind is initiated by the pressure gradient force (PGF) — air accelerates from high pressure toward low pressure due to differences in atmospheric pressure. The Coriolis force deflects the moving air (to the right in the Northern Hemisphere) but does not cause the initial motion. Centrifugal force acts in curved flow around pressure systems. Thermal effects create pressure differences which then drive the PGF. Without a pressure gradient there would be no wind.
 
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+#### Source
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+- [ ] ≈ [[Examen Blanc/Questionnaire toutes branches VV.pdf#page=5|VV Q15 p.5]] (clé: **A**)
 ### Q33: Above the friction layer, with a prevailing pressure gradient, the wind direction is ^t50q33
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q33) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q33)
@@ -646,6 +817,10 @@
 #### Key Terms
 
 AGL = Above Ground Level
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+#### Source
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+- [?] Source non identifiée
 ### Q34: Which of the listed surfaces causes the greatest wind speed reduction due to ground friction? ^t50q34
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q34) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q34)
@@ -663,6 +838,10 @@
 
 Surface roughness (aerodynamic roughness length) determines how much friction the surface exerts on moving air. Mountainous terrain with vegetation has the highest roughness length, causing maximum turbulent drag and wind speed reduction. Oceans have very low roughness and exert minimal friction. Flat vegetated land is intermediate. Importantly, mountains also mechanically block and deflect wind, creating additional complex flow patterns, turbulence, and wave phenomena of direct relevance to glider pilots.
 
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+#### Source
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+- [?] Source PDF non identifiée (original: **A**)
 ### Q35: The movement of air flowing together is called ^t50q35
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q35) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q35)
@@ -680,6 +859,10 @@
 
 Convergence describes air flowing into a region from different directions, compressing horizontally. By mass continuity, converging surface air must go somewhere — it is forced upward, triggering cloud formation, precipitation, and potentially convective development. Convergence zones are important for glider pilots as they produce enhanced lift along their axes; sea-breeze fronts and col zones between pressure systems are classic convergence sources for soaring.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q36: The movement of air flowing apart is called ^t50q36
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q36) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q36)
@@ -697,6 +880,10 @@
 
 Divergence describes air spreading outward from a region. At the surface, divergence causes subsiding air from above to replace the outflowing air, promoting stability, clear skies, and fair weather. High-pressure anticyclones are associated with surface divergence and upper-level convergence. In the upper troposphere, divergence above a surface low enhances upward motion and intensifies the low-pressure system.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q37: What weather development results from convergence at ground level? ^t50q37
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q37) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q37)
@@ -713,6 +900,13 @@
 #### Explanation
 
 Surface convergence forces air upward (ascending motion) by mass continuity — air cannot accumulate indefinitely at the surface. As air rises, it cools at the dry adiabatic lapse rate until it reaches the dew point (lifting condensation level), where condensation begins and clouds form. Further ascent releases latent heat, potentially fuelling deep convection. This is the fundamental mechanism behind frontal lifting and sea-breeze convergence lift.
+
+
+#### Source
+
+- Examen Blanc: [VV Q94 p.126](Questionnaire%20toutes%20branches%20VV.pdf#page=126) (score: 0.20)
+- [QuizVDS Q37](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q37): Answer A
+- PDF Answer: A
 
 ### Q38: When air masses meet each other head on, what is this referred to and what air movements follow? ^t50q38
 
@@ -731,6 +925,10 @@
 
 When two opposing air flows collide head-on, the meeting zone is a convergence line. The colliding air has nowhere to go horizontally and is forced upward — producing ascending motion, cloud formation, and potentially precipitation or thunderstorms. This occurs at fronts, sea-breeze convergence zones, and col zones. Glider pilots exploit convergence lines for extended linear climbs along the lift band.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q39: By which air masses is Central Europe mainly influenced? ^t50q39
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q39) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q39)
@@ -747,6 +945,13 @@
 #### Explanation
 
 Central Europe sits in the mid-latitude westerly belt between the polar front (cold polar air from the north) and subtropical high pressure (warm tropical air from the south). The interaction between these two contrasting air masses creates the characteristic mid-latitude cyclone (depression) weather of Central Europe: frontal systems, rapidly changing weather, and the full range of cloud types and precipitation. This dynamic contrast also drives the polar jet stream overhead.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q14 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.29)
+- [QuizVDS Q39](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q39): Answer D
+- PDF Answer: A
 
 ### Q40: In terms of global atmospheric circulation, where does polar cold air meet subtropical warm air? ^t50q40
 
@@ -765,6 +970,10 @@
 
 The polar front is the boundary between the polar cell (cold, dense air flowing equatorward) and the Ferrel cell (relatively warmer mid-latitude air). In the Northern Hemisphere it is located roughly between 40–60°N, but its position fluctuates as waves (Rossby waves) develop along it — these waves amplify into cyclones and anticyclones. The jet stream flows along the polar front and is a critical factor in synoptic weather patterns across Europe.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q41: "Foehn" conditions typically develop with ^t50q41
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q41) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q41)
@@ -782,6 +991,10 @@
 
 Foehn is a warm, dry, descending wind on the lee side of a mountain range. It develops when stable air is pushed by a broad-scale pressure gradient against a mountain barrier. On the windward side, moist air rises and cools at the Saturated Adiabatic Lapse Rate (SALR ~0.6°C/100 m) after reaching the dew point, precipitating moisture. On the lee side, dry air descends at the Dry Adiabatic Lapse Rate (DALR ~1°C/100 m), arriving warmer and drier than it started — the Foehn effect.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q42: What type of turbulence is typically encountered close to the ground on the lee side during Foehn conditions? ^t50q42
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q42) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q42)
@@ -799,6 +1012,10 @@
 
 During Foehn and mountain wave conditions, a rotor zone develops in the lower troposphere on the lee side beneath the crests of the standing waves. The rotor is a region of intense, chaotic turbulence with rotating air, strong downdrafts, and violent eddies — it is one of the most hazardous phenomena for aircraft. Lenticular clouds (altocumulus lenticularis) mark wave crests above, while rotor clouds (roll clouds) mark the rotor zone near the surface.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q43: Light turbulence should always be expected ^t50q43
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q43) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q43)
@@ -816,6 +1033,10 @@
 
 Cumulus clouds are the visible tops of thermal columns. The sub-cloud layer beneath them contains active thermals (updraughts) and compensating downdraughts between them, creating light to moderate turbulence from convective mixing. This is the normal turbulent environment of thermal soaring. Above cumulus tops the air is generally smoother (outside the cloud); stratiform clouds have minimal convective turbulence unless embedded CBs are present.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q44: Moderate to severe turbulence should be expected ^t50q44
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q44) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q44)
@@ -833,6 +1054,10 @@
 
 Rotor clouds (roll clouds) on the lee side of mountains are the visible indicator of the highly turbulent rotor zone beneath mountain waves. This turbulence can be extreme, with unpredictable up- and downdraughts, strong shear, and rotational forces capable of exceeding aircraft structural limits. Experienced wave pilots avoid or transit the rotor zone quickly with sufficient airspeed. The windward side of mountains typically has orographic cloud and steady lift, not severe turbulence.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q45: Which answer lists every state of water found in the atmosphere? ^t50q45
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q45) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q45)
@@ -849,6 +1074,13 @@
 #### Explanation
 
 Water exists in all three states within the Earth's atmosphere. Gaseous water vapour is invisible and present throughout the troposphere. Liquid water forms cloud droplets, rain, and drizzle. Solid water forms ice crystals (cirrus clouds), snow, hail, and graupel. Understanding all three states is essential for icing awareness: supercooled liquid water droplets (liquid below 0°C) pose the greatest structural icing hazard to aircraft, as they freeze on contact with cold surfaces.
+
+
+#### Source
+
+- Examen Blanc: [VV Q39 p.115](Questionnaire%20toutes%20branches%20VV.pdf#page=115) (score: 0.21)
+- [QuizVDS Q45](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q45): Answer A
+- PDF Answer: A
 
 ### Q46: How do dew point and relative humidity change when temperature decreases? ^t50q46
 
@@ -867,6 +1099,12 @@
 
 The dew point is the temperature to which air must be cooled (at constant pressure and moisture content) for saturation to occur. It is a measure of the absolute moisture content and remains constant as temperature changes (assuming no moisture is added or removed). However, relative humidity — the ratio of actual vapour pressure to saturation vapour pressure — increases as temperature falls, because the saturation vapour pressure decreases with temperature. When temperature equals the dew point, relative humidity reaches 100% and condensation begins.
 
+
+#### Source
+
+- Examen Blanc: [S2 Q15 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.33)
+- [QuizVDS Q46](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q46): Answer B
+
 ### Q47: How do spread and relative humidity change when temperature increases? ^t50q47
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q47) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q47)
@@ -883,6 +1121,12 @@
 #### Explanation
 
 Spread is the temperature-dew point difference (T - Td). As temperature increases while dew point remains constant, the spread widens. Simultaneously, because warmer air can hold more water vapour, the relative humidity decreases — the air is now further from saturation. A large spread indicates dry air and a high lifting condensation level (high cloud base). A small spread (near zero) indicates saturated or near-saturated conditions, with fog or low cloud likely.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q15 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.35)
+- [QuizVDS Q47](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q47): Answer C
 
 ### Q48: The "spread" is defined as ^t50q48
 
@@ -901,6 +1145,10 @@
 
 Spread (also called dew point depression) is simply the difference between the air temperature and the dew point temperature: Spread = T - Td. It is used to estimate cloud base height: in temperate latitudes, cloud base height in metres above the surface is approximately spread × 125 (or in feet, spread × 400). A spread of 0 means the air is saturated (fog or cloud at the surface). Spread is a quick indicator of moisture availability for soaring pilots.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q49: With other factors remaining constant, decreasing temperature results in ^t50q49
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q49) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q49)
@@ -918,6 +1166,10 @@
 
 As temperature decreases (with dew point unchanged), the gap between temperature and dew point narrows — spread decreases. At the same time, the saturation vapour pressure falls with temperature, so the actual vapour pressure now represents a higher fraction of the saturation value — relative humidity increases. This continues until the temperature reaches the dew point, spread becomes zero, relative humidity reaches 100%, and condensation occurs (cloud, fog, or dew).
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q50: What process causes latent heat to be released into the upper troposphere? ^t50q50
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q50) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q50)
@@ -935,6 +1187,10 @@
 
 When water vapour condenses into cloud droplets, the latent heat stored during evaporation is released into the surrounding air. In deep convective clouds (cumulonimbus), this release occurs in the upper troposphere and is enormous — it is the primary energy source that drives thunderstorm intensity and sustains tropical cyclones. The released latent heat warms the rising air parcel, making it more buoyant relative to the environment and accelerating further ascent, which is why the Saturated Adiabatic Lapse Rate (SALR) is less steep than the Dry Adiabatic Lapse Rate (DALR).
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q51: Which of these clouds poses the greatest danger to aviation? ^t50q51
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q51) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q51)
@@ -955,6 +1211,12 @@
 #### Key Terms
 
 CB = Cumulonimbus (thunderstorm cloud)
+
+#### Source
+
+- Examen Blanc: [S1C Q10 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 0.79)
+- PDF Answer: C
+
 ### Q52: In which situation is the tendency for thunderstorms most pronounced? ^t50q52
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q52) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q52)
@@ -971,6 +1233,12 @@
 #### Explanation
 
 Thunderstorms = slack pressure gradient (low pressure gradient) + strong surface heating (instability) + high humidity.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q19 p.23](Exa%20Blanc%20Série_1_Communes.pdf#page=23) (score: 1.00)
+- PDF Answer: C
 
 ### Q53: Fine suspended water droplets reduce visibility at an aerodrome to only 1.5 km up to 1000 ft AGL. What meteorological phenomenon causes this? ^t50q53
 
@@ -992,6 +1260,12 @@
 #### Key Terms
 
 AGL = Above Ground Level
+
+#### Source
+
+- Examen Blanc: [S1C Q11 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 0.52)
+- PDF Answer: A
+
 ### Q54: Which of the following situations most favours radiation fog formation? ^t50q54
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q54) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q54)
@@ -1008,6 +1282,12 @@
 #### Explanation
 
 Radiation fog: light wind (2 kt), small temperature/dew point spread (1°C), some cloud acceptable. Option **(C)** has too large a temp/dew point spread.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q12 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.60)
+- PDF Answer: B
 
 ### Q55: The temperature recorded at Samedan airport (LSZS, AD elevation 5600 ft) is +5°C. What will the approximate temperature be at 8600 ft altitude directly above the airport? (Assume ISA lapse rate) ^t50q55
 
@@ -1029,6 +1309,12 @@
 #### Key Terms
 
 ISA = International Standard Atmosphere
+
+#### Source
+
+- Examen Blanc: [S1C Q1 p.20](Exa%20Blanc%20Série_1_Communes.pdf#page=20) (score: 0.70)
+- PDF Answer: A
+
 ### Q56: The QFE of an aerodrome (AD elevation 3500 ft) corresponds to: ^t50q56
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q56) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q56)
@@ -1050,6 +1336,12 @@
 
 - **QFE** = Atmospheric pressure at aerodrome elevation
 - **ISA** = International Standard Atmosphere
+
+#### Source
+
+- Examen Blanc: [S1C Q2 p.20](Exa%20Blanc%20Série_1_Communes.pdf#page=20) (score: 0.73)
+- PDF Answer: C
+
 ### Q57: What does the following wind barb symbol mean? ^t50q57
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q57) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q57)
@@ -1081,6 +1373,12 @@
 
 Reference: [Wikipedia — Station model § Wind](https://en.wikipedia.org/wiki/Station_model#Wind)
 
+
+#### Source
+
+- Examen Blanc: [S1C Q6 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 1.00)
+- PDF Answer: C
+
 ### Q58: What are the wind speed and direction in the following METAR? LSZB 131220Z 28015G25KT 9999 SCT035 BKN075 10/06 Q1018 NOSIG= ^t50q58
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q58) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q58)
@@ -1101,6 +1399,12 @@
 #### Key Terms
 
 METAR = Aerodrome routine weather report
+
+#### Source
+
+- Examen Blanc: [S1C Q3 p.20](Exa%20Blanc%20Série_1_Communes.pdf#page=20) (score: 0.82)
+- PDF Answer: D
+
 ### Q59: In Switzerland, cloud base in a METAR is given in ^t50q59
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q59) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q59)
@@ -1122,6 +1426,12 @@
 
 - **AGL** = Above Ground Level
 - **METAR** = Aerodrome routine weather report
+
+#### Source
+
+- Examen Blanc: [S1C Q9 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 0.83)
+- PDF Answer: C
+
 ### Q60: You are flying at very high altitude (northern hemisphere) and consistently have a crosswind from the left. You conclude that: ^t50q60
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q60) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q60)
@@ -1138,6 +1448,12 @@
 #### Explanation
 
 Buys-Ballot's law: standing with your back to the wind in the northern hemisphere, the low-pressure area is to your left. Wind from the left = low pressure to the left, high pressure to the right.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q5 p.20](Exa%20Blanc%20Série_1_Communes.pdf#page=20) (score: 0.53)
+- PDF Answer: D
 
 ### Q61: Based on the synoptic chart, what change in atmospheric pressure is likely at point C in the coming hours? ^t50q61
 
@@ -1167,6 +1483,12 @@
 - **Option C** (pressure rise) would apply to a location behind a cold front where cold dense air moves in.
 - **Option D** (rapid irregular variations) is more typical of the immediate vicinity of thunderstorm activity, not the broad-scale approach of a warm front.
 
+
+#### Source
+
+- Examen Blanc: [S1C Q15 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.38)
+- PDF Answer: D
+
 ### Q62: Which phenomenon is typical during the summer passage of an unstable cold front? ^t50q62
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q62) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q62)
@@ -1186,6 +1508,12 @@
 An unstable cold front in summer forces warm, moist, unstable air upward vigorously, triggering strong convection and the development of cumuliform clouds including towering cumulus and cumulonimbus with showers and thunderstorms.
 - Stratiform cloud cover **(A)** is associated with stable air masses and warm fronts, not unstable cold fronts.
 - Behind a cold front temperatures drop rather than rise **(C)**, and pressure rises rather than drops **(D)** as cooler, denser air replaces the warm sector.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q13 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.27)
+- PDF Answer: D
 
 ### Q63: What is most likely to happen when a stable, warm, humid air mass slides over a cold air mass? ^t50q63
 
@@ -1209,6 +1537,12 @@
 - **Option C** describes unstable convective weather typical of cold fronts, not warm fronts.
 - **Option D** combines fog with drying aloft, which is internally contradictory and not a recognised frontal pattern.
 
+
+#### Source
+
+- Examen Blanc: [S1C Q18 p.23](Exa%20Blanc%20Série_1_Communes.pdf#page=23) (score: 0.43)
+- PDF Answer: D
+
 ### Q64: Which air mass is likely to produce showers in Central Europe in any season? ^t50q64
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q64) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q64)
@@ -1229,6 +1563,12 @@
 - Continental tropical air **(A)** is warm and dry, producing clear skies rather than showers.
 - Maritime tropical air **(B)** is warm and moist but tends to produce stratiform clouds and drizzle, not showers.
 - Continental polar air **(C)** is cold and dry, lacking the moisture content needed for significant precipitation without first crossing open water.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q14 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.56)
+- PDF Answer: A
 
 ### Q65: Given this synoptic chart for the Alpine region, what hazards are you likely to encounter in Switzerland? ^t50q65
 
@@ -1256,6 +1596,12 @@
 - **Option A** describes a south-side precipitation event (Stau from the south), not a northwest situation.
 - **Option B** misplaces the thunderstorms on the wrong side of the Alps.
 - **Option D** reverses the pattern — clouds would cover the north side, not the south.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q17 p.23](Exa%20Blanc%20Série_1_Communes.pdf#page=23) (score: 0.52)
+- PDF Answer: C
 
 ### Q66: Referring to the Low Level SWC chart, which statement is correct? ^t50q66
 
@@ -1296,6 +1642,10 @@
 #### Key Terms
 
 FL = Flight Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q67: On a sunny summer afternoon you are on final approach to an aerodrome whose runway runs parallel to the coastline, with the coast to your left. On this flat terrain, what direction will the thermal (sea breeze) wind come from? ^t50q67
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q67) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q67)
@@ -1318,6 +1668,12 @@
 
 - **Option D** would require the sea to be on the right side.
 
+
+#### Source
+
+- Examen Blanc: [S1C Q4 p.20](Exa%20Blanc%20Série_1_Communes.pdf#page=20) (score: 0.40)
+- PDF Answer: B
+
 ### Q68: Where are you most likely to experience strong winds and low-level turbulence? ^t50q68
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q68) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q68)
@@ -1338,6 +1694,12 @@
 - The centre of an anticyclone **(A)** is characterised by calm, subsiding air with light winds.
 - The centre of a depression **(C)** can have calm conditions in the eye area despite surrounding storminess.
 - Slack pressure gradients **(D)** by definition produce weak winds, not strong ones.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q7 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 0.57)
+- PDF Answer: D
 
 ### Q69: An air mass at 10°C has a relative humidity of 45%. If the temperature rises to 20°C without any moisture change, how will the relative humidity be affected? ^t50q69
 
@@ -1361,6 +1723,12 @@
 
 - **Option B** is incorrect because relative humidity is temperature-dependent and cannot stay constant when temperature changes without a corresponding moisture change.
 
+
+#### Source
+
+- Examen Blanc: [S1C Q8 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 0.50)
+- PDF Answer: B
+
 ### Q70: On 1 June (summer time), you receive the Swiss GAFOR valid from 06:00 to 12:00 UTC. Your planned route shows "XMD". What does this mean? ^t50q70
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q70) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q70)
@@ -1381,6 +1749,12 @@
 
 - **Option A and D** incorrectly interpret the timing or the code.
 - **Option B** confuses the category — "M" is not "critical.".
+
+
+#### Source
+
+- Examen Blanc: [S1C Q16 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.54)
+- PDF Answer: B
 
 ### Q71: What does the wind barb symbol below represent? ^t50q71
 
@@ -1416,6 +1790,12 @@
 
 Reference: [Wikipedia — Station model § Wind](https://en.wikipedia.org/wiki/Station_model#Wind)
 
+
+#### Source
+
+- Examen Blanc: [S1C Q6 p.21](Exa%20Blanc%20Série_1_Communes.pdf#page=21) (score: 0.25)
+- PDF Answer: C
+
 ### Q72: At what time of day or night is radiation fog most likely to form? ^t50q72
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q72) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q72)
@@ -1437,6 +1817,10 @@
 - **Option C** (after sunset) is usually too early for sufficient cooling.
 - **Option D** (sunrise) is when radiation fog is often densest, but it typically starts forming well before dawn.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q73: Which typical Swiss weather pattern does the sketch below depict? ^t50q73
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q73) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q73)
@@ -1459,6 +1843,11 @@
 - **Option A** (North Foehn) involves warm descending air on the south side of the Alps.
 - **Option B** (Westerly wind) is associated with Atlantic depressions.
 - **Option C** (South Foehn) produces warm dry wind on the north side of the Alps from southerly flow.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q13 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.71)
 
 ### Q74: Which altimeter setting causes the instrument to display the airport elevation when on the ground? ^t50q74
 
@@ -1486,6 +1875,12 @@
 - **QFE** = Atmospheric pressure at aerodrome elevation
 - **MSL** = Mean Sea Level
 - **QNE** = Standard pressure setting (1013.25 hPa)
+
+#### Source
+
+- Examen Blanc: [VV Q20 p.111](Questionnaire%20toutes%20branches%20VV.pdf#page=111) (score: 0.25)
+- PDF Answer: C
+
 ### Q75: Which statement correctly describes the clouds in this METAR? LSGC 040620Z 23005KT 9000 -RA BKN012 09/08 Q1018= ^t50q75
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q75) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q75)
@@ -1512,6 +1907,10 @@
 
 - **AGL** = Above Ground Level
 - **METAR** = Aerodrome routine weather report
+
+#### Source
+
+- [?] Source non identifiée
 ### Q76: Looking at the chart, how will atmospheric pressure at point A change in the next hour? ^t50q76
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q76) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q76)
@@ -1525,15 +1924,31 @@
 
 #### Answer
 
-A)
+D)
 
 #### Explanation
 
-The synoptic chart shows a frontal system approaching point A, with a low-pressure centre or trough moving toward it. As a front and its associated low approach, pressure at a given location falls due to decreasing atmospheric mass overhead.
+The synoptic chart shows a **Norwegian cyclone model** (mid-latitude depression): a low-pressure centre with warm and cold fronts trailing from it. Point A is located **on the cold front**.
 
-- **Option B** (rapid regular variations) is not a standard pressure pattern associated with frontal approach.
-- **Option C** (no change) would only apply if no weather systems were moving.
-- **Option D** (rise) would occur after the cold front has passed, not before.
+In this model, pressure behaviour depends on position relative to the fronts:
+- **Ahead of warm front** (warm front approaching): pressure falls steadily
+- **In warm sector** (between warm and cold fronts): pressure continues falling
+- **On/just behind cold front** (cold front passing): pressure is at its lowest and begins to **rise**
+- **Behind cold front** (traîne): pressure rises as cold, dense air moves in
+
+Since A is on the cold front, the front will pass in the next hour. Cold dense air replaces warm air → pressure **rises**.
+
+- **A** (fall) would apply if A were ahead of the warm front or in the warm sector.
+- **B** (rapid regular variations) is not a standard pressure pattern for frontal passage.
+- **C** (no change) would only apply if no weather systems were moving.
+
+Ref: [NOAA — Norwegian Cyclone Model](https://www.noaa.gov/jetstream/synoptic/norwegian-cyclone-model)
+
+
+#### Source
+
+- Examen Blanc: [S1C Q15 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.24)
+- PDF Answer: D
 
 ### Q77: What weather phenomena can you expect within zone 1 (south of France) at an altitude of 3500 ft AMSL? ^t50q77
 
@@ -1563,6 +1978,10 @@
 - **AMSL** = Above Mean Sea Level
 - **CB** = Cumulonimbus (thunderstorm cloud)
 - **FL** = Flight Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q78: Which cloud type consists entirely of ice crystals? ^t50q78
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q78) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q78)
@@ -1581,6 +2000,12 @@
 Cirrus clouds form at very high altitudes (typically above 6,000 m / 20,000 ft) where temperatures are far below freezing, so they consist exclusively of ice crystals, giving them their characteristic thin, wispy, fibrous appearance.
 - Cumulonimbus **(A)** contains both supercooled water droplets and ice crystals across its enormous vertical extent.
 - Stratus **(B)** and altocumulus **(D)** form at lower and mid-level altitudes respectively, where temperatures usually support liquid water droplets.
+
+
+#### Source
+
+- Examen Blanc: [VV Q146 p.137](Questionnaire%20toutes%20branches%20VV.pdf#page=137) (score: 0.46)
+- PDF Answer: C
 
 ### Q79: With which cloud type is drizzle most commonly associated? ^t50q79
 
@@ -1602,6 +2027,13 @@
 - Cirrocumulus **(C)** is a high-altitude ice crystal cloud that produces no precipitation reaching the ground.
 - Altocumulus **(D)** is a mid-level cloud that occasionally produces virga but not sustained drizzle.
 
+
+#### Source
+
+- Examen Blanc: [VV Q62 p.120](Questionnaire%20toutes%20branches%20VV.pdf#page=120) (score: 0.27)
+- [QuizVDS Q68](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q68): Answer C
+- PDF Answer: D
+
 ### Q80: Which of these phenomena signals a high risk of thunderstorm development? ^t50q80
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q80) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q80)
@@ -1622,6 +2054,11 @@
 - Stratus **(B)** indicates a stable, stratified atmosphere suppressing convection.
 - A halo **(D)** forms when light passes through cirrostratus ice crystals and signals an approaching warm front, not imminent thunderstorm development.
 
+
+#### Source
+
+- Examen Blanc: [S2 Q10 p.26](Exa%20Blanc%20Série_2.pdf#page=26) (score: 0.48)
+
 ### Q81: Which of the following phase transitions requires an input of heat? ^t50q81
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q81) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q81)
@@ -1638,6 +2075,12 @@
 #### Explanation
 
 The transition from liquid to gaseous state (evaporation or boiling) is endothermic — it requires the input of latent heat of vaporisation to break intermolecular bonds and allow molecules to escape into the gas phase. Gaseous to liquid (A, condensation) releases latent heat. Liquid to solid (B, freezing) releases latent heat of fusion. Gaseous to solid (D, deposition) also releases heat. Only evaporation **(C)** absorbs energy from the environment.
+
+
+#### Source
+
+- Examen Blanc: [VV Q40 p.115](Questionnaire%20toutes%20branches%20VV.pdf#page=115) (score: 0.46)
+- PDF Answer: C
 
 ### Q82: On which slopes in the diagram are the strongest updrafts found? ^t50q82
 
@@ -1658,6 +2101,10 @@
 
 Slopes 4 and 1 produce the strongest updrafts because slope 4 faces the prevailing wind (the windward slope), generating orographic lift as air is forced upward, while slope 1 faces the sun, producing thermal updrafts from differential surface heating. Slopes 2 and 3, being on the lee side or in shadow, experience descending air or weaker heating respectively, resulting in downdrafts or much weaker uplift.
 
+
+#### Source
+
+- [?] Source PDF non identifiée (original: **B**)
 ### Q83: What conditions are typically found behind an active, unstable cold front? ^t50q83
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q83) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q83)
@@ -1678,6 +2125,11 @@
 - **Option A** describes stable warm-sector or warm-front conditions.
 - **Option C** is wrong because pressure rises (not drops) after a cold front passes as denser cold air moves in.
 - **Option D** is incorrect because temperatures fall (not rise) behind a cold front.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q13 p.26](Exa%20Blanc%20Série_2.pdf#page=26) (score: 0.27)
 
 ### Q84: An aircraft flies at FL 70 from Bern (QNH 1012 hPa) to Marseille (QNH 1027 hPa). While maintaining FL 70, does the true altitude above sea level change? ^t50q84
 
@@ -1703,6 +2155,11 @@
 
 - **QNH** = Pressure adjusted to mean sea level
 - **FL** = Flight Level
+
+#### Source
+
+- Examen Blanc: [S2 Q13 p.26](Exa%20Blanc%20Série_2.pdf#page=26) (score: 0.25)
+
 ### Q85: An air mass at +2°C has a relative humidity of 35%. If the temperature drops to -5°C, how does the relative humidity change? ^t50q85
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q85) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q85)
@@ -1723,6 +2180,11 @@
 - **Options A and D** wrongly state that humidity decreases with cooling.
 
 - **Option B** is incorrect because relative humidity is always temperature-dependent.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q15 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.50)
 
 ### Q86: A cold air mass moves over a warmer land surface and is heated from below. How does this affect the air mass? ^t50q86
 
@@ -1746,6 +2208,11 @@
 - **Option B** is incorrect because warming increases the air's capacity to hold moisture, reducing relative humidity.
 - **Option D** has no direct relationship to surface heating of an air mass.
 
+
+#### Source
+
+- Examen Blanc: [S2 Q16 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.50)
+
 ### Q87: On 1 July (summer time) you receive the Swiss GAFOR valid from 06:00 to 12:00 UTC. Your planned route shows "XXM". What does this mean? ^t50q87
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q87) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q87)
@@ -1764,6 +2231,11 @@
 The GAFOR validity (06:00–12:00 UTC) splits into three two-hour blocks. In summer time (CEST = UTC+2): block 1 = 08–10 LT, block 2 = 10–12 LT, block 3 = 12–14 LT. "XXM" means X (closed) for block 1, X (closed) for block 2, M (mountain conditions/difficult) for block 3. At 11:00 LT (= 09:00 UTC), we are in block 2, which is X = closed. However, the answer key selects B, indicating that at 11:00 LT the conditions are classified as "critical" per the GAFOR coding.
 
 - **Options A, C, and D** misidentify either the time block or the condition code.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q17 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.45)
 
 ### Q88: How do the volume and temperature of a descending air mass change? ^t50q88
 
@@ -1785,6 +2257,11 @@
 - **Option A** incorrectly states temperature decreases.
 - **Option B** reverses both changes.
 - **Option D** incorrectly states volume increases.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q18 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.71)
 
 ### Q89: A radiosonde at high altitude in the Northern Hemisphere has high pressure to its north and low pressure to its south. In which direction will the wind carry the balloon? ^t50q89
 
@@ -1808,6 +2285,11 @@
 #### Key Terms
 
 D — Drag
+
+#### Source
+
+- Examen Blanc: [S3 Q19 p.27](Exa%20Blanc%20Série_3.pdf#page=27) (score: 0.61)
+
 ### Q90: Which temperature profile above an aerodrome presents the greatest risk of freezing rain? ^t50q90
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q90) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q90)
@@ -1827,6 +2309,10 @@
 
 Freezing rain requires a specific temperature layering: a warm layer aloft (above 0°C) where snow melts into rain, underlain by a shallow sub-zero layer near the surface where the rain becomes supercooled but does not refreeze until it contacts surfaces. Profile A shows exactly this dangerous configuration — a temperature inversion with warm air above freezing overlying a cold surface layer. The other profiles lack this critical warm-over-cold sandwich structure that produces supercooled rain droplets capable of instant freezing on contact with aircraft or ground surfaces.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q91: Which of the following phase transitions releases heat into the environment? ^t50q91
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q91) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q91)
@@ -1843,6 +2329,12 @@
 #### Explanation
 
 Condensation — the transition from gaseous to liquid state — is an exothermic process that releases latent heat into the surrounding environment. This released heat is what was originally absorbed during evaporation and is a key energy source driving thunderstorm development. Solid to gaseous (A, sublimation), liquid to gaseous (B, evaporation), and solid to liquid (C, melting) all absorb heat from the environment rather than releasing it.
+
+
+#### Source
+
+- Examen Blanc: [VV Q40 p.115](Questionnaire%20toutes%20branches%20VV.pdf#page=115) (score: 0.36)
+- PDF Answer: C
 
 ### Q92: Where in the diagram are the strongest downdraughts located? ^t50q92
 
@@ -1863,6 +2355,10 @@
 
 In the terrain/airflow diagram, position 3 is located on the leeward side of the ridge where the airflow descends and accelerates. This lee-side subsidence and rotor zone produces the strongest downdraughts as gravity pulls the dense descending air downward while it compresses and accelerates. Positions 1 and 4 are on the windward slope where updrafts dominate. Position 2 is near the ridge crest where airflow transitions from ascending to descending. Lee-side downdraughts are a significant hazard for glider pilots attempting ridge crossings.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q93: Looking at the chart, how will the atmospheric pressure at point B change in the next hour? ^t50q93
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q93) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q93)
@@ -1885,6 +2381,12 @@
 - **Option A** (rapid variations) is associated with convective activity, not the smooth pressure field of an anticyclone.
 - **Option B** (fall) would apply if a depression were approaching.
 - **Option D** (no change) is unlikely given the movement of a significant pressure system toward point B.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q15 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.25)
+- PDF Answer: D
 
 ### Q94: An aircraft flies at FL 90 from Zurich (QNH 1020 hPa) to Munich (QNH 1005 hPa). While maintaining FL 90, does the true altitude above sea level change? ^t50q94
 
@@ -1910,6 +2412,10 @@
 - **QNH** = Pressure adjusted to mean sea level
 - **FL** = Flight Level
 - **MSL** = Mean Sea Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q95: An air mass at 18°C has a relative humidity of 29%. If the temperature rises to 28°C with no change in moisture, how is the relative humidity affected? ^t50q95
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q95) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q95)
@@ -1929,6 +2435,11 @@
 
 - **Options A and D** incorrectly state that humidity increases.
 - **Option B** is wrong because relative humidity always changes when temperature changes without a corresponding moisture change.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q15 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.44)
 
 ### Q96: A warm air mass moves over a colder land surface and cools from below. How does this affect the air mass? ^t50q96
 
@@ -1951,6 +2462,11 @@
 - **Option C** has no direct relationship.
 - **Option D** contradicts the stable conditions produced by surface cooling.
 
+
+#### Source
+
+- Examen Blanc: [S2 Q16 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.36)
+
 ### Q97: On 1 August (summer time) you receive the Swiss GAFOR valid from 06:00 to 12:00 UTC. Your planned route shows "DDO". What does this mean? ^t50q97
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q97) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q97)
@@ -1969,6 +2485,11 @@
 The GAFOR validity (06:00–12:00 UTC) covers three two-hour blocks. In CEST (UTC+2): block 1 = 08–10 LT, block 2 = 10–12 LT, block 3 = 12–14 LT. "DDO" means D (difficult) for block 1, D (difficult) for block 2, O (open) for block 3. At 13:00 LT (= 11:00 UTC), block 3 applies, and the route is O = open.
 
 - **Options A, B, and C** misidentify either the time block or the condition category for the given time.
+
+
+#### Source
+
+- Examen Blanc: [S2 Q17 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.36)
 
 ### Q98: How do the volume and temperature of a rising air mass change? ^t50q98
 
@@ -1989,6 +2510,11 @@
 
 - **Options A and B** incorrectly state volume decreases (it expands).
 - **Option C** incorrectly states temperature increases (it cools).
+
+
+#### Source
+
+- Examen Blanc: [S2 Q18 p.27](Exa%20Blanc%20Série_2.pdf#page=27) (score: 0.60)
 
 ### Q99: Under otherwise equal conditions, which type of precipitation is least hazardous for aviation? ^t50q99
 
@@ -2011,6 +2537,10 @@
 - Rain showers **(B)** from convective clouds are associated with turbulence, wind shear, and reduced visibility.
 Of all four, drizzle poses the least threat to flight safety.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q100: In which situation is the risk of encountering freezing rain greatest? ^t50q100
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q100) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q100)
@@ -2027,6 +2557,11 @@
 #### Explanation
 
 Freezing rain forms when warm air aloft (above 0°C) overrides a shallow layer of sub-zero air at the surface. This temperature structure is the hallmark of a winter warm front, where warm moist air glides over a wedge of cold surface air. Rain falling from the warm layer passes through the freezing layer and becomes supercooled, freezing instantly on contact with aircraft surfaces. Summer warm fronts **(A)** rarely have sub-zero surface temperatures. Cold fronts (B, D) involve cold air undercutting warm air, which does not create the necessary warm-over-cold layering.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q10 p.24](Exa%20Blanc%20Série_3.pdf#page=24) (score: 0.35)
 
 ### Q101: What does the wind barb symbol below represent? ^t50q101
 
@@ -2062,6 +2597,11 @@
 
 Reference: [Wikipedia — Station model § Wind](https://en.wikipedia.org/wiki/Station_model#Wind)
 
+
+#### Source
+
+- Examen Blanc: [S3 Q10 p.24](Exa%20Blanc%20Série_3.pdf#page=24) (score: 0.29)
+
 ### Q102: What is the name of the fog that develops when a moist air mass moves horizontally over a colder surface? ^t50q102
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q102) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q102)
@@ -2081,6 +2621,11 @@
 - Radiation fog **(A)** forms on calm, clear nights from radiative ground cooling, not from horizontal air movement.
 - Orographic fog **(B)** results from moist air being lifted over terrain.
 - Sea spray **(D)** is not a fog type — it refers to water droplets mechanically ejected from wave crests.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q12 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.55)
 
 ### Q103: Which typical Swiss weather pattern does the sketch below show? ^t50q103
 
@@ -2104,6 +2649,11 @@
 - **Option A** (westerly wind) involves Atlantic air masses from the west.
 - **Option B** (Bise) is a cold northeast wind.
 - **Option D** (North Foehn) reverses the flow, with air descending on the southern side of the Alps.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q13 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.64)
 
 ### Q104: Which altimeter setting must you select so that the instrument shows your height above a specific aerodrome (AAL)? ^t50q104
 
@@ -2130,6 +2680,11 @@
 - **QFE** = Atmospheric pressure at aerodrome elevation
 - **QNH** = Pressure adjusted to mean sea level
 - **QNE** = Standard pressure setting (1013.25 hPa)
+
+#### Source
+
+- Examen Blanc: [S3 Q14 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.23)
+
 ### Q105: What are the wind speed and direction in this METAR? LFSB 171100Z 29004KT 220V340 9999 FEW043 28/17 Q1013 NOSIG= ^t50q105
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q105) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q105)
@@ -2153,6 +2708,11 @@
 #### Key Terms
 
 METAR = Aerodrome routine weather report
+
+#### Source
+
+- Examen Blanc: [S3 Q14 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.46)
+
 ### Q106: During summer in central Europe, what phenomenon is typical of an advancing cold front when the warm air ahead has an unstable thermodynamic structure? ^t50q106
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q106) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q106)
@@ -2172,6 +2732,11 @@
 - Stratiform clouds **(A)** are associated with stable air masses.
 - Temperature falls, not rises **(B)**, after a cold front passes.
 - Pressure rises, not drops **(D)**, behind a cold front as cold dense air replaces the warm sector.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q16 p.26](Exa%20Blanc%20Série_3.pdf#page=26) (score: 0.44)
 
 ### Q107: Along the route from LOWK to EDDP (dotted arrow), what weather phenomena should be anticipated? ^t50q107
 
@@ -2197,6 +2762,11 @@
 
 - **Option D** correctly predicts cooling and thunderstorms but wrongly identifies a tailwind.
 
+
+#### Source
+
+- Examen Blanc: [S3 Q17 p.26](Exa%20Blanc%20Série_3.pdf#page=26) (score: 0.36)
+
 ### Q108: Which type of cloud is most likely to cause heavy showers? ^t50q108
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q108) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q108)
@@ -2216,6 +2786,12 @@
 - Nimbostratus **(A)** produces prolonged, steady precipitation but not heavy showers.
 - Altostratus **(B)** is a mid-level layer cloud producing light to moderate continuous precipitation.
 - Cirrocumulus **(C)** is a high-altitude cloud that does not produce significant precipitation.
+
+
+#### Source
+
+- Examen Blanc: [VV Q63 p.120](Questionnaire%20toutes%20branches%20VV.pdf#page=120) (score: 0.38)
+- PDF Answer: A
 
 ### Q109: A radiosonde at high altitude in the Northern Hemisphere has a low pressure area to its north and a high pressure area to its south. In which direction will the wind carry the balloon? ^t50q109
 
@@ -2239,6 +2815,11 @@
 #### Key Terms
 
 D — Drag
+
+#### Source
+
+- Examen Blanc: [S3 Q19 p.27](Exa%20Blanc%20Série_3.pdf#page=27) (score: 0.61)
+
 ### Q110: When air is forced upward by terrain and encounters unstable, moist layers, what are the resulting thunderstorms called? ^t50q110
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q110) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q110)
@@ -2256,6 +2837,10 @@
 
 When terrain (mountains, ridges, or hills) mechanically forces air upward and this lifted air encounters moist, unstable layers aloft, the resulting convective storms are classified as orographic thunderstorms. They are driven by topographic lifting rather than by frontal forcing (A, D) or purely thermal surface heating **(C)**. Orographic thunderstorms are common over mountainous regions in summer and can be particularly persistent because the terrain continuously feeds the lifting mechanism.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q111: Which set of conditions favours the development of advection fog? ^t50q111
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q111) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q111)
@@ -2275,6 +2860,12 @@
 - Cold air over warm water **(A)** would produce steam fog (evaporation fog), not advection fog.
 - Moisture evaporating from warm ground into cold air **(B)** describes steam or mixing fog.
 - Cooling on a cloudy night **(D)** is unlikely to produce fog because cloud cover prevents the radiative cooling needed.
+
+
+#### Source
+
+- Examen Blanc: [S3 Q12 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.20)
+- [QuizVDS Q55](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q55): Answer D
 
 ### Q112: Which process leads to the formation of advection fog? ^t50q112
 
@@ -2297,6 +2888,10 @@
 - **Option C** describes radiation fog, formed by nocturnal radiative cooling on clear, calm nights.
 - **Option D** (cold air over warm ground) would warm the air, decreasing relative humidity and moving conditions away from fog formation.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q113: During the passage of a cold front, what pressure pattern is typically observed? ^t50q113
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q113) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q113)
@@ -2316,6 +2911,10 @@
 
 - **Options A and D** describe monotonic trends, while option C suggests no dynamic weather activity, none of which match frontal passage behaviour.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q114: Which frontal boundary separates subtropical air from polar cold air, particularly across Central Europe? ^t50q114
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q114) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q114)
@@ -2335,6 +2934,13 @@
 - A cold front **(B)** is the leading edge of a single advancing cold air mass within a cyclone.
 - A warm front **(D)** is the leading edge of advancing warm air.
 - An occlusion **(C)** forms when a cold front overtakes a warm front — none of these are the large-scale climatological boundary itself.
+
+
+#### Source
+
+- Examen Blanc: [VV Q95 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 0.27)
+- [QuizVDS Q90](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q90): Answer D
+- PDF Answer: B
 
 ### Q115: In Central Europe during summer, what weather conditions are typically associated with high pressure areas? ^t50q115
 
@@ -2358,6 +2964,10 @@
 - **Option B** describes strong westerlies associated with low-pressure systems.
 - **Option D** describes a cold northerly flow pattern, not typical of summer anticyclones.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q116: What weather can be expected in high pressure areas during the winter season? ^t50q116
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q116) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q116)
@@ -2380,6 +2990,10 @@
 
 - **Option D** describes summer high-pressure conditions with thermal cumulus development, not the foggy, grey winter anticyclone.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q117: At which temperature range is airframe icing most hazardous? ^t50q117
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q117) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q117)
@@ -2400,6 +3014,10 @@
 - The range +5° to -10°C **(A)** extends into above-freezing temperatures where icing cannot occur.
 - The range +20° to -5°C **(C)** is far too broad and mostly above freezing.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q118: When large, supercooled droplets strike the leading surfaces of an aircraft, which type of ice is produced? ^t50q118
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q118) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q118)
@@ -2420,6 +3038,10 @@
 - Mixed ice **(B)** is a combination of both.
 - Hoar frost **(C)** forms by direct deposition of water vapour onto cold surfaces, not from droplet impact.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q119: What conditions must be present for thermal thunderstorms to develop? ^t50q119
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q119) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q119)
@@ -2437,6 +3059,10 @@
 
 Thermal thunderstorms require three ingredients working together: a conditionally unstable atmosphere (one that becomes fully unstable once air parcels reach saturation and the level of free convection), elevated surface temperatures to trigger strong thermals, and high humidity to supply the moisture and latent heat energy that fuels deep convection. An absolutely stable atmosphere (B, C) would suppress all convective development regardless of temperature or humidity. Low temperature and humidity **(D)** would deny the storm both its trigger mechanism and its energy source.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q120: During which stage of a thunderstorm do updrafts dominate? ^t50q120
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q120) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q120)
@@ -2456,6 +3082,10 @@
 - The mature stage **(A)** features coexisting updrafts and downdrafts along with precipitation, turbulence, and lightning.
 - The dissipating stage **(C)** is dominated by downdrafts as the updraft weakens and precipitation drags air downward. "Upwind stage" **(B)** is not a recognised term in thunderstorm lifecycle nomenclature.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q121: Where should heavy downdrafts and strong wind shear near the ground be expected? ^t50q121
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q121) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q121)
@@ -2476,6 +3106,10 @@
 - Radiation fog nights **(D)** are calm with virtually no wind shear.
 - High, flattened Cu **(A)** indicates suppressed convection under an inversion — weak updrafts and no significant downdrafts.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q122: Which weather chart displays the actual MSL air pressure together with pressure centres and fronts? ^t50q122
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q122) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q122)
@@ -2499,6 +3133,10 @@
 #### Key Terms
 
 MSL = Mean Sea Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q123: What kind of information can be derived from satellite images? ^t50q123
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q123) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q123)
@@ -2519,6 +3157,10 @@
 - Temperature and dew point **(B)** are measured by radiosondes and surface stations.
 - Visibility conditions **(D)** can only be roughly inferred, not directly measured, from satellite imagery.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q124: Which information is available in the ATIS but not in a METAR? ^t50q124
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q124) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q124)
@@ -2540,6 +3182,10 @@
 
 - **ATIS** = Automatic Terminal Information Service
 - **METAR** = Aerodrome routine weather report
+
+#### Source
+
+- [?] Source non identifiée
 ### Q125: Which cloud type signals the presence of thermal updrafts? ^t50q125
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q125) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q125)
@@ -2560,6 +3206,13 @@
 - Cirrus **(D)** is a high-altitude ice crystal cloud unrelated to surface convection.
 - Lenticularis **(A)** forms in the crests of mountain wave oscillations in stable airflow, indicating wave lift rather than thermals.
 
+
+#### Source
+
+- Examen Blanc: [VV Q70 p.121](Questionnaire%20toutes%20branches%20VV.pdf#page=121) (score: 0.21)
+- [QuizVDS Q122](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q122): Answer C
+- PDF Answer: A
+
 ### Q126: Compared to the dry adiabatic lapse rate, the saturated adiabatic lapse rate is ^t50q126
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q126) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q126)
@@ -2577,6 +3230,10 @@
 
 The saturated (moist) adiabatic lapse rate (SALR, averaging about 0.6°C/100 m) is lower than the dry adiabatic lapse rate (DALR, 1.0°C/100 m) because as saturated air rises and cools, water vapour condenses and releases latent heat, which partially offsets the cooling due to expansion. This means saturated air cools more slowly per unit of altitude gained. The two rates are not equal **(A)**, the SALR is not higher **(C)**, and saying they are merely "proportional" **(D)** is imprecise and misleading.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q127: What is the value of the dry adiabatic lapse rate? ^t50q127
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q127) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q127)
@@ -2598,6 +3255,12 @@
 - **Option B** (0.65°C/100 m) is the standard atmosphere environmental lapse rate.
 - **Option D** (2°/1000 ft) converts to about 0.66°C/100 m, which does not match the DALR.
 
+
+#### Source
+
+- Examen Blanc: [S1S Q1 p.40](Exa%20Blanc%20Série_1_Specifiques.pdf#page=40) (score: 0.25)
+- [QuizVDS Q52](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q52): Answer B
+
 ### Q128: What weather should be expected when the atmosphere is conditionally unstable? ^t50q128
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q128) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q128)
@@ -2618,6 +3281,10 @@
 - Layered clouds with prolonged rain **(B)** characterise absolutely stable (stratiform) weather.
 - Shallow mid-level cumulus **(D)** indicates limited instability insufficient for significant vertical development.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q129: Identify the cloud type shown in the picture.. ^t50q129
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q129) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q129)
@@ -2643,6 +3310,12 @@
 #### Key Terms
 
 FL = Flight Level
+
+#### Source
+
+- Examen Blanc: [VV Q146 p.137](Questionnaire%20toutes%20branches%20VV.pdf#page=137) (score: 0.29)
+- PDF Answer: C
+
 ### Q130: What is required for the development of medium to large precipitation particles? ^t50q130
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q130) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q130)
@@ -2663,6 +3336,10 @@
 - A high cloud base **(B)** reduces available cloud depth for particle growth.
 - Strong horizontal wind **(D)** does not contribute to the vertical suspension needed for particle growth.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q131: On the weather chart, the symbol labelled (2) represents a / an ^t50q131
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q131) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q131)
@@ -2685,6 +3362,10 @@
 - An occlusion **(D)** uses alternating triangles and semicircles on the same side.
 - A front aloft **(C)** is marked with a different symbology indicating the front does not reach the surface.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q132: Within the warm sector of a polar front low during summer, what visual flight conditions are typical? ^t50q132
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q132) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q132)
@@ -2708,6 +3389,13 @@
 #### Key Terms
 
 VFR = Visual Flight Rules
+
+#### Source
+
+- Examen Blanc: [VV Q99 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 0.21)
+- [QuizVDS Q77](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q77): Answer B
+- PDF Answer: D
+
 ### Q133: After a cold front has passed, what visual flight conditions are typical? ^t50q133
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q133) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q133)
@@ -2729,6 +3417,10 @@
 - **Option C** understates the convective activity typical of post-frontal polar air.
 - **Option D** describes poor visibility with stratus, which is more typical of the cold sector of a warm occlusion, not the fresh polar air behind a cold front.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q134: In what direction does a polar front low typically move? ^t50q134
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q134) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q134)
@@ -2748,6 +3440,13 @@
 
 - **Option A** wrongly states southward movement.
 - **Options B and C** propose rigid seasonal rules that oversimplify the highly variable tracks of mid-latitude cyclones across Europe.
+
+
+#### Source
+
+- Examen Blanc: [VV Q54 p.118](Questionnaire%20toutes%20branches%20VV.pdf#page=118) (score: 0.20)
+- [QuizVDS Q80](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q80): Answer A
+- PDF Answer: D
 
 ### Q135: What is the characteristic pressure pattern as a polar front low passes over? ^t50q135
 
@@ -2771,6 +3470,10 @@
 - **Option C** has pressure falling behind the cold front, contradicting the arrival of dense cold air.
 - **Option D** reverses the entire pattern.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q136: As a polar front low passes through Central Europe, what wind direction changes are typically observed? ^t50q136
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q136) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q136)
@@ -2788,6 +3491,10 @@
 
 In the Northern Hemisphere, as a typical polar front low passes, wind veers (shifts clockwise) at both frontal passages. At the warm front, wind veers from southeast to south or southwest. At the cold front, it veers again from southwest to west or northwest. This consistent clockwise shift indicates the low is passing to the north of the observer, which is the normal track for lows crossing Central Europe. Backing (A, B, C) would indicate the low passing to the south — an uncommon trajectory.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q137: What pressure pattern may develop from cold-air intrusion in the upper troposphere? ^t50q137
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q137) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q137)
@@ -2807,6 +3514,10 @@
 - An upper high **(B)** would form from warm-air advection, not cold intrusion.
 - Oscillating pressure **(C)** and a large surface low **(D)** are not the direct or primary consequence of upper-level cold intrusion.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q138: Cold air flowing into the upper troposphere may lead to ^t50q138
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q138) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q138)
@@ -2826,6 +3537,10 @@
 - Stabilisation and settled weather **(A)** and calm conditions **(D)** are the opposite of what cold upper-air intrusion produces.
 - Frontal weather **(B)** requires surface air-mass boundaries, which are not a direct result of upper-tropospheric cooling.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q139: How does an influx of cold air affect the shape and vertical spacing of pressure layers? ^t50q139
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q139) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q139)
@@ -2842,6 +3557,13 @@
 #### Explanation
 
 Cold air is denser than warm air, so a cold air column has less vertical distance (decreased spacing) between any two pressure surfaces. Because the column is compressed, the upper pressure surfaces lie at lower geometric heights, which is identified as low pressure aloft on hypsometric charts. This is why upper-level lows are always associated with cold-core air masses. Warm air produces the opposite: increased spacing and raised heights (high pressure aloft), as described in options A and C.
+
+
+#### Source
+
+- Examen Blanc: [VV Q53 p.118](Questionnaire%20toutes%20branches%20VV.pdf#page=118) (score: 0.21)
+- [QuizVDS Q88](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q88): Answer C
+- PDF Answer: D
 
 ### Q140: During summer, what weather is typical of high pressure areas? ^t50q140
 
@@ -2863,6 +3585,10 @@
 - Frontal passages **(C)** are features of low-pressure troughs.
 - Widespread high fog **(D)** is a winter high-pressure phenomenon caused by temperature inversions trapping cold moist air.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q141: On the windward side of a mountain range during Foehn conditions, what weather should be expected? ^t50q141
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q141) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q141)
@@ -2884,6 +3610,10 @@
 - **Option A** describes convective (unstable) weather, not the organised forced ascent of a Foehn pattern.
 - **Option B** describes stagnant anticyclonic conditions, not active orographic lifting.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q142: Which chart depicts areas of precipitation? ^t50q142
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q142) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q142)
@@ -2904,6 +3634,10 @@
 - A wind chart **(A)** displays wind patterns only.
 - A GAFOR **(C)** is a coded route forecast for general aviation that categorises flying conditions but does not depict precipitation areas graphically.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q143: An inversion is an atmospheric layer where ^t50q143
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q143) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q143)
@@ -2925,6 +3659,13 @@
 - **Option C** describes the normal lapse rate.
 - **Option A** is incorrect because atmospheric pressure always decreases with height, regardless of the temperature profile.
 
+
+#### Source
+
+- Examen Blanc: [VV Q122 p.132](Questionnaire%20toutes%20branches%20VV.pdf#page=132) (score: 0.43)
+- [QuizVDS Q121](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q121): Answer C
+- PDF Answer: D
+
 ### Q144: Which condition may prevent radiation fog from forming? ^t50q144
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q144) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q144)
@@ -2941,6 +3682,13 @@
 #### Explanation
 
 Radiation fog requires the ground to radiate longwave heat to space, cooling the surface air to the dew point. An overcast cloud layer acts as a blanket, absorbing and re-emitting radiation back toward the ground, preventing the surface from cooling sufficiently. Therefore, overcast cloud cover prevents radiation fog formation. A clear night **(A)**, low spread **(B)**, and calm wind **(D)** all favour fog formation — they are prerequisites, not preventative conditions.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q12 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.22)
+- [QuizVDS Q63](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q63): Answer D
+- PDF Answer: B
 
 ### Q145: On the chart, the symbol labelled (3) represents a / an ^t50q145
 
@@ -2964,6 +3712,10 @@
 - A cold front **(B)** uses only triangles.
 - A front aloft **(D)** has a distinct marking indicating the frontal surface does not reach the ground.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q146: A boundary between a cold polar air mass and a warm subtropical air mass that shows no horizontal movement is known as a ^t50q146
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q146) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q146)
@@ -2983,6 +3735,13 @@
 - A cold front **(D)** is specifically an advancing cold air mass pushing warm air aside.
 - A warm front **(A)** is advancing warm air overriding cold air.
 - An occluded front **(B)** results from a cold front overtaking a warm front within a mature cyclone — it involves merging fronts, not stationary boundaries.
+
+
+#### Source
+
+- Examen Blanc: [VV Q95 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 0.24)
+- [QuizVDS Q79](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q79): Answer C
+- PDF Answer: B
 
 ### Q147: Which situation may lead to severe wind shear? ^t50q147
 
@@ -3004,6 +3763,10 @@
 - Thirty minutes after a shower **(C)**, conditions have typically stabilised.
 - Cirrus ahead of a warm front **(D)** is an upper-level indicator without immediate low-level shear implications.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q148: Which kind of visibility reduction is largely unaffected by temperature changes? ^t50q148
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q148) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q148)
@@ -3021,6 +3784,10 @@
 
 Haze (HZ) is caused by dry particulates — dust, smoke, industrial pollution, and fine sand — suspended in the atmosphere. Because these particles are not moisture-dependent, haze persists regardless of temperature changes. Mist **(A)**, fog patches **(B)**, and radiation fog **(D)** are all formed by water droplet suspension and are highly sensitive to temperature: warming evaporates the droplets and improves visibility, while cooling promotes further condensation and worsens it.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q149: In a METAR, how are moderate showers of rain encoded? ^t50q149
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q149) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q149)
@@ -3041,6 +3808,10 @@
 #### Key Terms
 
 METAR = Aerodrome routine weather report
+
+#### Source
+
+- [?] Source non identifiée
 ### Q150: For which areas are SIGMET warnings issued? ^t50q150
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q150) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q150)
@@ -3065,6 +3836,10 @@
 - **ATC** = Air Traffic Control
 - **ICAO** = International Civil Aviation Organization
 - **SIGMET** = Significant Meteorological Information
+
+#### Source
+
+- [?] Source non identifiée
 ### Q151: Updrafts along a mountain slope can be strengthened by ^t50q151
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q151) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q151)
@@ -3086,6 +3861,10 @@
 - **Option B** (nighttime radiation from the windward side) produces cooling and katabatic (downslope) flow, the opposite of updrafts.
 - **Option C** (solar heating on the lee side) does not contribute to windward-side updrafts.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q152: The prefix used for clouds in the high layers is ^t50q152
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q152) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q152)
@@ -3110,6 +3889,10 @@
 #### Key Terms
 
 FL = Flight Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q153: What factor may limit the vertical extent of cumulus clouds at the top? ^t50q153
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q153) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q153)
@@ -3130,6 +3913,10 @@
 - **Option D** (the spread, i.e., temperature minus dew point) determines cloud base height, not cloud top.
 - **Options B** (absolute humidity) and C (relative humidity) influence whether clouds form at all but do not cap their vertical extent the way an inversion does.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q154: Which factors point toward a tendency for fog formation? ^t50q154
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q154) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q154)
@@ -3151,6 +3938,10 @@
 - **Option B** (low pressure with rising temperature) widens the spread and favours lifting rather than surface fog.
 - **Option D** (rising temperature) increases the spread, moving conditions away from saturation.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q155: What process gives rise to orographic fog (hill fog)? ^t50q155
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q155) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q155)
@@ -3172,6 +3963,10 @@
 - **Option B** describes steam fog (or evaporation fog), which forms when cold air passes over much warmer water or moist surfaces.
 - **Option C** describes frontal or mixing fog, a different process entirely.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q156: What is needed for precipitation to form inside clouds? ^t50q156
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q156) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q156)
@@ -3193,6 +3988,10 @@
 - **Option B** (an inversion layer) suppresses cloud development and works against precipitation.
 - **Option D** (calm winds and sunshine) describes surface conditions that do not directly produce in-cloud precipitation.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q157: In areas where isobars are widely spaced, what wind conditions should be expected? ^t50q157
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q157) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q157)
@@ -3212,6 +4011,10 @@
 
 - **Options A, B, and C** all describe strong prevailing winds, which require closely spaced isobars (a steep pressure gradient) and are therefore inconsistent with the wide spacing described.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q158: Under what circumstances does back side weather (Rückseitenwetter) occur? ^t50q158
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q158) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q158)
@@ -3233,6 +4036,10 @@
 - **Option B** (Foehn on the lee side) is a thermodynamic mountain phenomenon unrelated to frontal weather.
 - **Option C** (before an occlusion) describes pre-frontal conditions, not back-side weather.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q159: How is a wind reported as 225/15 described? ^t50q159
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q159) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q159)
@@ -3252,6 +4059,13 @@
 
 - **Options B and C** incorrectly interpret 225 degrees as northeast, perhaps confusing the direction the wind blows from with the direction it blows toward.
 - **Option A** gives the correct direction but uses km/h instead of the standard aviation unit of knots.
+
+
+#### Source
+
+- Examen Blanc: [VV Q54 p.118](Questionnaire%20toutes%20branches%20VV.pdf#page=118) (score: 0.36)
+- [QuizVDS Q126](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q126): Answer B
+- PDF Answer: D
 
 ### Q160: In the Bavarian area near the Alps, what weather typically accompanies Foehn conditions? ^t50q160
 
@@ -3274,6 +4088,10 @@
 - **Option B** describes a synoptic pattern, not the weather itself.
 - **Option C** contradicts the definition of Foehn, which produces warm, dry — not cold, humid — descending air.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q161: Clouds are fundamentally classified into which two basic types? ^t50q161
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q161) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q161)
@@ -3295,6 +4113,10 @@
 - **Option B** uses non-standard terminology.
 - **Option C** names specific weather phenomena rather than fundamental cloud forms.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q162: During Foehn conditions, what weather phenomenon marked as "2" should be expected on the lee side?. ^t50q162
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q162) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q162)
@@ -3317,6 +4139,10 @@
 - **Options B and D** (cumulonimbus) are associated with deep convective instability, not the stable laminar wave flow characteristic of Foehn.
 - **Option A** (Altocumulus castellanus) indicates mid-level convective instability with turret-like protrusions, which is a different meteorological situation.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q163: When very small water droplets and ice crystals strike the leading surfaces of an aircraft, which type of ice forms? ^t50q163
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q163) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q163)
@@ -3338,6 +4164,10 @@
 - **Option D** (mixed ice) is a combination of rime and clear ice.
 - **Option A** (hoar frost) forms by direct deposition of water vapour onto cold surfaces, not by droplet impact.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q164: Which chart contains information about pressure patterns and frontal positions? ^t50q164
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q164) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q164)
@@ -3362,6 +4192,10 @@
 #### Key Terms
 
 MSL = Mean Sea Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q165: What is the typical cloud sequence observed during the approach and passage of a warm front? ^t50q165
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q165) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q165)
@@ -3383,6 +4217,10 @@
 - **Option B** describes a coastal sea-breeze cycle unrelated to frontal meteorology.
 - **Option D** describes anticyclonic subsidence or continental high-pressure conditions.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q166: What phenomenon results from cold-air downdrafts carrying precipitation from a fully developed thunderstorm cloud? ^t50q166
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q166) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q166)
@@ -3404,6 +4242,10 @@
 - **Option C** (electrical discharge) results from charge separation within the cloud.
 - **Option B** (freezing rain) requires a specific temperature inversion profile, not downdraft spreading.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q167: Which item is NOT included on Low-Level Significant Weather Charts (LLSWC)? ^t50q167
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q167) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q167)
@@ -3421,6 +4263,10 @@
 
 Low-Level Significant Weather Charts are forecast products that depict meteorological hazards below a specified altitude, including frontal systems and their movement (option A), turbulence areas (option B), and icing conditions (option C). However, they do not contain radar echoes of precipitation (option D) because radar imagery is a real-time observational product, whereas LLSWC are prognostic charts prepared in advance. Precipitation areas may be indicated symbolically on LLSWC, but actual radar returns are found only on separate radar displays.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q168: Which cloud type produces prolonged, steady rain? ^t50q168
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q168) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q168)
@@ -3441,6 +4287,13 @@
 - **Option A** (cirrostratus) is a thin, high-level ice cloud that does not produce surface precipitation.
 - **Option B** (altocumulus) is a mid-level cloud that occasionally produces virga but not sustained surface rain.
 - **Option D** (cumulonimbus) produces intense but short-lived showers and thunderstorms rather than prolonged steady rain.
+
+
+#### Source
+
+- Examen Blanc: [VV Q70 p.121](Questionnaire%20toutes%20branches%20VV.pdf#page=121) (score: 0.21)
+- [QuizVDS Q68](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q68): Answer C
+- PDF Answer: A
 
 ### Q169: Based on cloud type, how is precipitation classified? ^t50q169
 
@@ -3463,6 +4316,10 @@
 - **Option B** uses redundant terminology that does not distinguish cloud origins.
 - **Option C** classifies by precipitation phase (snow versus rain), not by cloud type.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q170: Which conditions favour thunderstorm development? ^t50q170
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q170) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q170)
@@ -3486,6 +4343,12 @@
 - **Option B** features a strong inversion that would cap any vertical development.
 - **Option C** describes a stable, overcast situation with stratus or altostratus, which suppresses thunderstorm formation.
 
+
+#### Source
+
+- Examen Blanc: [VV Q138 p.136](Questionnaire%20toutes%20branches%20VV.pdf#page=136) (score: 0.21)
+- PDF Answer: C
+
 ### Q171: When isobars on a surface weather chart are widely spaced, what does this indicate about the prevailing wind? ^t50q171
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q171) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q171)
@@ -3507,6 +4370,10 @@
 - **Option C** pairs a strong gradient with light wind, which is meteorologically incorrect.
 - **Option D** reverses the gradient-wind relationship.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q172: An air mass arriving in Central Europe from the Russian continent during winter is described as ^t50q172
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q172) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q172)
@@ -3526,6 +4393,13 @@
 
 - **Option B** (maritime polar) originates over polar oceans and carries significant moisture.
 - **Option A** (continental tropical) and option D (maritime tropical) originate in warm regions and are far too warm and/or moist to describe Siberian winter air.
+
+
+#### Source
+
+- Examen Blanc: [S1C Q14 p.22](Exa%20Blanc%20Série_1_Communes.pdf#page=22) (score: 0.32)
+- [QuizVDS Q70](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q70): Answer B
+- PDF Answer: A
 
 ### Q173: What clouds and weather are typically observed during the passage of a cold front? ^t50q173
 
@@ -3548,6 +4422,10 @@
 - **Option B** describes anticyclonic or high-pressure settling conditions.
 - **Option D** describes a coastal sea-breeze pattern unrelated to frontal weather.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q174: When an aircraft is struck by lightning, what is the most immediate danger? ^t50q174
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q174) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q174)
@@ -3569,6 +4447,10 @@
 - **Option B** (cabin depressurisation) applies primarily to pressurised aircraft and is not the most common immediate consequence.
 - **Option D** (explosion of cockpit equipment) is extremely unlikely in certified aircraft with proper lightning protection.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q175: What is meant by mountain wind? ^t50q175
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q175) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q175)
@@ -3590,6 +4472,10 @@
 - **Option C** reverses the nighttime flow direction.
 - **Option D** reverses the daytime flow direction.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q176: What is the average value of the saturated adiabatic lapse rate? ^t50q176
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q176) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q176)
@@ -3610,6 +4496,12 @@
 - **Option A** (0 degrees C per 100 m) would mean no temperature change with altitude, which is physically unrealistic for a rising air parcel.
 - **Option B** (2 degrees C per 1000 ft, approximately 0.66 degrees C per 100 m) is a rough approximation but not the standard textbook value.
 - **Option C** (1.0 degrees C per 100 m) is the dry adiabatic lapse rate, not the saturated rate.
+
+
+#### Source
+
+- Examen Blanc: [S1S Q1 p.40](Exa%20Blanc%20Série_1_Specifiques.pdf#page=40) (score: 0.23)
+- [QuizVDS Q51](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q51): Answer D
 
 ### Q177: Throughout the year, extensive high pressure areas are found ^t50q177
 
@@ -3632,6 +4524,10 @@
 - **Option C** (mid-latitudes along the polar front) is a zone of cyclonic activity and low pressure.
 - **Option D** (areas with extensive lifting) produce low pressure by definition, not high pressure.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q178: During flight, weather and operational information about the destination aerodrome can be obtained via ^t50q178
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q178) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q178)
@@ -3660,6 +4556,10 @@
 - **FIR** = Flight Information Region
 - **SIGMET** = Significant Meteorological Information
 - **VOLMET** = Weather broadcasts for aircraft in flight
+
+#### Source
+
+- [?] Source non identifiée
 ### Q179: Identify the cloud type shown in the picture.. ^t50q179
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q179) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q179)
@@ -3683,6 +4583,12 @@
 - **Option C** (stratus) would present as a uniform, featureless grey layer.
 - **Option D** ("altus") is not a recognized cloud genus in the international cloud classification system.
 
+
+#### Source
+
+- Examen Blanc: [VV Q146 p.137](Questionnaire%20toutes%20branches%20VV.pdf#page=137) (score: 0.20)
+- PDF Answer: C
+
 ### Q180: What determines the character of an air mass? ^t50q180
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q180) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q180)
@@ -3704,6 +4610,10 @@
 - **Option C** (environmental lapse rate at source) is a consequence of the air mass properties, not their cause.
 - **Option D** (temperatures at origin and present location) captures only temperature while ignoring the critical moisture dimension.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q181: What cloud type is commonly observed across extensive high-pressure areas in summer? ^t50q181
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q181) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q181)
@@ -3721,6 +4631,10 @@
 
 In summer anticyclones, surface heating generates thermal convection that produces scattered fair-weather Cumulus clouds (Cu humilis or Cu mediocris) during the day, dissipating in the evening. Overcast low stratus (option D) is associated with stable, moist air at low levels, common in autumn or maritime high-pressure situations. Nimbostratus (option B) is associated with frontal systems. Squall lines and thunderstorms (option A) require convective instability and moisture not typical of settled high-pressure conditions.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q182: The symbol marked (1) in the figure represents which frontal type? ^t50q182
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q182) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q182)
@@ -3740,6 +4654,10 @@
 
 On a surface weather chart, a cold front is depicted by a line with solid triangular spikes (barbs) pointing in the direction of movement. The symbol labeled (1) in figure matches the cold front symbol. A warm front uses semicircles. An occlusion uses alternating triangles and semicircles. A front aloft is depicted differently and is less commonly shown on basic surface charts.
 
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+#### Source
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+- [?] Source non identifiée
 ### Q183: In METAR code, which identifier denotes heavy rain? ^t50q183
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q183) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q183)
@@ -3760,6 +4678,10 @@
 #### Key Terms
 
 METAR = Aerodrome routine weather report
+
+#### Source
+
+- [?] Source non identifiée
 ### Q184: During which stage of a thunderstorm do strong updrafts and downdrafts coexist? ^t50q184
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q184) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q184)
@@ -3777,6 +4699,10 @@
 
 In the mature stage of a thunderstorm, both strong updrafts (sustaining the storm) and strong downdrafts (driven by precipitation drag and evaporative cooling) coexist simultaneously within the Cumulonimbus cell. The initial (cumulus) stage has only updrafts. The dissipating stage is dominated by downdrafts only, which cut off the updraft supply and weaken the storm. 'Thunderstorm stage' (option A) is not a recognised meteorological term.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q185: Which conditions are most conducive to aircraft icing? ^t50q185
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q185) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q185)
@@ -3794,6 +4720,10 @@
 
 The most severe icing occurs between 0°C and -12°C where supercooled liquid water droplets are most abundant and drop size is largest, producing clear or mixed icing on airframe surfaces. Below -20°C, cloud water is mostly in ice crystal form and causes much less accretion. Above 0°C, droplets are not supercooled and do not freeze on contact. Icing in clear air (option D) does not occur as there are no supercooled droplets. Cirrus (option C) contains ice crystals which do not adhere significantly.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q186: What is the primary hazard when approaching a valley airfield with strong winds aloft blowing perpendicular to the surrounding ridges? ^t50q186
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q186) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q186)
@@ -3811,6 +4741,10 @@
 
 When strong wind blows perpendicular to a mountain ridge, orographic lift on the windward side and mechanical turbulence create complex wind shear on the lee side. An aircraft descending into a valley airfield on the lee side may encounter severe wind shear with the wind reversing by up to 180° between altitudes, creating sudden loss of airspeed or ground wind opposite to the upper-level flow. Reduced visibility (option C) is a secondary concern. Icing (option D) is unrelated to mountain wind shear. Heavy downdrafts in rainfall (option A) describes thunderstorm activity, not orographic flow.
 
+
+#### Source
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+- [?] Source non identifiée
 ### Q187: What are "blue thermals"? ^t50q187
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q187) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q187)
@@ -3832,6 +4766,12 @@
 
 - **Option B** describes sink between Cu clouds.
 - **Option A** describes clear-air turbulence (CAT) near thunderstorms, a different phenomenon.
+
+
+#### Source
+
+- Examen Blanc: [VV Q127 p.133](Questionnaire%20toutes%20branches%20VV.pdf#page=133) (score: 0.20)
+- PDF Answer: B
 
 ### Q188: The expression "beginning of thermals" refers to the moment when thermal strength ^t50q188
 
@@ -3856,6 +4796,10 @@
 
 - **AGL** = Above Ground Level
 - **MSL** = Mean Sea Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q189: How is the "trigger temperature" defined? It is the temperature which ^t50q189
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q189) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q189)
@@ -3877,6 +4821,10 @@
 
 - **Option D** describes thunderstorm formation, not Cu formation.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q190: In a weather briefing, what does the term "over-development" refer to? ^t50q190
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q190) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q190)
@@ -3898,6 +4846,10 @@
 - **Option D** refers to synoptic-scale deepening of depressions.
 - **Option B** describes the spreading of Cu under an inversion (which is actually 'street' or 'cover' formation, a separate phenomenon).
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q191: In gliding meteorology, what does "shielding" refer to? ^t50q191
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q191) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q191)
@@ -3919,6 +4871,10 @@
 - **Option A** describes the anvil of a Cb, not shielding.
 - **Option B** describes sky coverage in oktas, which is unrelated.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q192: What is the gaseous composition of dry air? ^t50q192
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q192) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q192)
@@ -3935,6 +4891,13 @@
 #### Explanation
 
 Dry air is composed of approximately 78% nitrogen, 21% oxygen, and 1% argon and trace gases including carbon dioxide. This is the standard atmospheric composition. All other options incorrectly swap the proportions of nitrogen and oxygen or introduce water vapour as a major component. Water vapour is a variable constituent (0–4%) not included in the standard dry air composition.
+
+
+#### Source
+
+- Examen Blanc: [VV Q8 p.108](Questionnaire%20toutes%20branches%20VV.pdf#page=108) (score: 0.41)
+- [QuizVDS Q11](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q11): Answer B
+- PDF Answer: D
 
 ### Q193: Under ISA conditions at mean sea level, what is the mass of one cubic metre of air? ^t50q193
 
@@ -3960,6 +4923,10 @@
 
 - **ISA** = International Standard Atmosphere
 - **MSL** = Mean Sea Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q194: How is the tropopause defined? ^t50q194
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q194) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q194)
@@ -3979,6 +4946,10 @@
 
 - **Option B** confuses the tropopause with the stratopause.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q195: What characterises an inversion layer? ^t50q195
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q195) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q195)
@@ -4000,6 +4971,13 @@
 - **Option C** describes an isothermal layer.
 - **Option A** describes a generic boundary without specifying the temperature gradient direction.
 
+
+#### Source
+
+- Examen Blanc: [VV Q30 p.113](Questionnaire%20toutes%20branches%20VV.pdf#page=113) (score: 0.30)
+- [QuizVDS Q121](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q121): Answer C
+- PDF Answer: D
+
 ### Q196: What defines an isothermal layer? ^t50q196
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q196) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q196)
@@ -4019,6 +4997,12 @@
 
 - **Option B** describes a generic atmospheric boundary layer, not a layer of constant temperature.
 
+
+#### Source
+
+- Examen Blanc: [VV Q30 p.113](Questionnaire%20toutes%20branches%20VV.pdf#page=113) (score: 0.33)
+- PDF Answer: D
+
 ### Q197: What fundamental force initiates wind? ^t50q197
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q197) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q197)
@@ -4036,6 +5020,10 @@
 
 Wind is caused by the pressure gradient force — air flows from areas of high pressure to areas of low pressure, and the greater the pressure difference over a given distance, the stronger the resulting wind. The Coriolis force (option B) deflects wind but does not create it. Centrifugal force (option C) is a secondary effect in curved flow. There is no meteorological force specifically called 'thermal force'; thermal differences drive pressure gradients, but the direct cause of wind is the pressure gradient itself.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q198: Under what conditions does Foehn typically develop? ^t50q198
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q198) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q198)
@@ -4053,6 +5041,10 @@
 
 Foehn develops when a stable airflow is forced over a mountain barrier. On the windward side, the air rises moist-adiabatically (condensation releasing latent heat), and on the lee side it descends dry-adiabatically, arriving warmer and drier than before ascent. Stability is necessary for the organised flow; instability would break the flow into convective cells. Calm high-pressure conditions (options B and C) do not provide the cross-mountain pressure gradient needed. Instability (option D) would prevent the laminar flow characteristic of Foehn.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q199: How is the "spread" (dew-point depression) defined? ^t50q199
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q199) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q199)
@@ -4074,6 +5066,10 @@
 - **Option B** describes relative humidity.
 - **Option A** describes the saturation mixing ratio or absolute humidity capacity.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q200: During Foehn, what weather phenomenon designated by "2" should be expected on the lee side?. ^t50q200
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q200) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q200)
@@ -4093,6 +5089,13 @@
 
 This question is identical in content to question 90. During Foehn, the descending and warming lee-side flow is stable and generates standing wave clouds. Altocumulus lenticularis forms in the crests of these mountain waves on the lee side. Cumulonimbus (options C and D) requires strong convective instability absent in Foehn descent. Altocumulus Castellanus (option A) indicates mid-level instability, not the stable wave motion of a Foehn situation.
 
+
+#### Source
+
+- Examen Blanc: [VV Q70 p.121](Questionnaire%20toutes%20branches%20VV.pdf#page=121) (score: 0.20)
+- [QuizVDS Q58](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q58): Answer C
+- PDF Answer: A
+
 ### Q201: Which factor can prevent radiation fog from forming? ^t50q201
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q201) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q201)
@@ -4110,6 +5113,10 @@
 
 Radiation fog forms on clear, calm nights when the ground radiates heat to space, cooling the surface air to its dew point. An overcast cloud cover prevents the necessary radiative cooling of the ground surface by acting as an insulating blanket, reflecting long-wave radiation back to the ground. Calm wind (option B) is actually a prerequisite for radiation fog formation. A clear night (option D) and low spread (option A) are also favourable, not preventative, conditions.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q202: Through what process does advection fog form? ^t50q202
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q202) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q202)
@@ -4133,6 +5140,11 @@
 - **Option A** describes radiation fog.
 - The defining factor in advection fog is the movement of warm moist air over cold ground.
 
+
+#### Source
+
+- Examen Blanc: [S3 Q12 p.25](Exa%20Blanc%20Série_3.pdf#page=25) (score: 0.25)
+
 ### Q203: What process leads to the development of orographic fog (hill fog)? ^t50q203
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q203) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q203)
@@ -4155,6 +5167,10 @@
 - **Option B** describes mixing fog.
 - The key process is forced lifting of moist air over elevated terrain.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q204: What weather phenomena are associated with an upper-level trough? ^t50q204
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q204) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q204)
@@ -4175,6 +5191,10 @@
 - **Options B and D** describe stable, anticyclonic conditions.
 - **Option C** (high stratus) would require stable, moist conditions near the surface, not the convective instability associated with a cold upper trough.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q205: On the windward side of a mountain range during Foehn, what weather should be expected? ^t50q205
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q205) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q205)
@@ -4196,6 +5216,10 @@
 - **Option D** describes stable, fog-prone conditions unrelated to Foehn.
 - **Option C** describes conditions more typical of frontal convective activity.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q206: Which chart presents observed MSL pressure distribution and the corresponding frontal systems? ^t50q206
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q206) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q206)
@@ -4216,6 +5240,10 @@
 #### Key Terms
 
 MSL = Mean Sea Level
+
+#### Source
+
+- [?] Source non identifiée
 ### Q207: In METAR, how is heavy rain encoded? ^t50q207
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q207) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q207)
@@ -4236,6 +5264,10 @@
 #### Key Terms
 
 METAR = Aerodrome routine weather report
+
+#### Source
+
+- [?] Source non identifiée
 ### Q208: In METAR, how are moderate rain showers encoded? ^t50q208
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q208) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q208)
@@ -4256,6 +5288,10 @@
 #### Key Terms
 
 METAR = Aerodrome routine weather report
+
+#### Source
+
+- [?] Source non identifiée
 ### Q209: Under what conditions does back-side weather (Ruckseitenwetter) occur? ^t50q209
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q209) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q209)
@@ -4273,6 +5309,10 @@
 
 Back-side weather (Rückseitenwetter) describes the weather in the cold air mass following the passage of a cold front: cold, unstable polar or arctic air with scattered showers, good visibility, and gusty winds — often excellent soaring conditions for gliders in the convective back-side air. It occurs after, not before, frontal passages. An occlusion (option D) combines warm and cold front characteristics. Foehn (option B) is a separate orographic phenomenon. After a warm front (option A) brings the warm sector, not cold back-side air.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q210: In the International Standard Atmosphere, how does temperature change from MSL to approximately 10,000 m altitude? ^t50q210
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q210) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q210)
@@ -4297,6 +5337,12 @@
 
 - **ISA** = International Standard Atmosphere
 - **MSL** = Mean Sea Level
+
+#### Source
+
+- Examen Blanc: [S2 Q4 p.37](Exa%20Blanc%20Série_2.pdf#page=37) (score: 0.33)
+- [QuizVDS Q127](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q127): Answer D
+
 ### Q211: What weather should be expected during Foehn conditions in the Bavarian region near the Alps? ^t50q211
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q211) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q211)
@@ -4318,6 +5364,10 @@
 - **Option B** describes the synoptic pressure setup only partially.
 - **Option A** places the Ns on the north (lee) side, which is incorrect.
 
+
+#### Source
+
+- [?] Source non identifiée
 ### Q212: Which meteorological element is most important for the safety of a VFR flight? ^t50q212
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q212) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q212)
@@ -4336,6 +5386,12 @@
 For visual flight rules (VFR), horizontal visibility is the most critical element: below the regulatory minimum, the pilot can no longer maintain separation from terrain, obstacles, and other aircraft by sight alone. Wind direction, temperature, and cloud cover above 1500 m are important, but it is low clouds and reduced visibility that directly trigger VFR restrictions. The amount and height of clouds below 1500 m/GND (ceiling) is also critical, as a low ceiling can trap the pilot.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q1 p.107](Questionnaire%20toutes%20branches%20VV.pdf#page=107) (score: 1.00)
+- PDF Answer: B
 
 ### Q213: Which meteorological situation reduces visibility the most? ^t50q213
 
@@ -4356,6 +5412,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q3 p.107](Questionnaire%20toutes%20branches%20VV.pdf#page=107) (score: 1.00)
+- PDF Answer: A
+
 ### Q214: From which altitude can the danger of gaseous embolism occur? ^t50q214
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q214) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q214)
@@ -4374,6 +5436,12 @@
 Gaseous embolism (blood boiling) occurs when ambient pressure drops below the vapour pressure of human blood (approximately 47 hPa). This corresponds to about 19,000 m under standard conditions, but serious physiological problems related to extreme low pressure (outgassing of tissues) begin to manifest around 13,000 m/AMSL. This is why this altitude is used as the critical danger threshold in aviation regulations.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q10 p.109](Questionnaire%20toutes%20branches%20VV.pdf#page=109) (score: 0.78)
+- PDF Answer: B
 
 ### Q215: In a mercury barometer, what is found in the tube above the mercury? ^t50q215
 
@@ -4394,6 +5462,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q11 p.109](Questionnaire%20toutes%20branches%20VV.pdf#page=109) (score: 0.79)
+- PDF Answer: A
+
 ### Q216: Which instrument is used to measure barometric air pressure? ^t50q216
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q216) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q216)
@@ -4412,6 +5486,12 @@
 The mercury barometer measures atmospheric pressure by balancing the weight of a mercury column against air pressure. The thermometer measures temperature, the psychrometer measures relative humidity (by the difference between dry-bulb and wet-bulb thermometers), and the Magdeburg hemispheres were a historical demonstration of atmospheric pressure, not a standard measuring instrument.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q12 p.109](Questionnaire%20toutes%20branches%20VV.pdf#page=109) (score: 0.86)
+- PDF Answer: A
 
 ### Q217: Which instrument is used to measure wind speed at a meteorological station? ^t50q217
 
@@ -4432,6 +5512,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q48 p.117](Questionnaire%20toutes%20branches%20VV.pdf#page=117) (score: 0.88)
+- PDF Answer: D
+
 ### Q218: What is the chart commonly used to compile wind statistics for a given location (e.g., an airport)? ^t50q218
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q218) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q218)
@@ -4450,6 +5536,12 @@
 The wind polygon (frequency rose) shows, for each directional sector, the frequency and average speed of winds observed over a long period at a given location - very useful for planning runway orientation. The wind rose is the figure showing the 16 cardinal and intercardinal directions, but it is not a statistical chart. The wind triangle is an air navigation tool (drift calculation). Isotachs are lines of equal wind speed on a weather chart.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q51 p.117](Questionnaire%20toutes%20branches%20VV.pdf#page=117) (score: 0.83)
+- PDF Answer: B
 
 ### Q219: What is meant by the "polar front jet stream"? ^t50q219
 
@@ -4470,6 +5562,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q57 p.119](Questionnaire%20toutes%20branches%20VV.pdf#page=119) (score: 0.58)
+- PDF Answer: C
+
 ### Q220: At what height above an obstacle are mechanical turbulences strongest? ^t50q220
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q220) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q220)
@@ -4488,6 +5586,12 @@
 Mechanical turbulence generated by airflow around an obstacle (building, tree, hill) is most intense in the immediate downstream zone, up to approximately 150 m above the top of the obstacle. In this zone, eddies and wind shear are at a maximum. Beyond this, turbulence gradually decreases with altitude. For approach and landing, it is therefore recommended to maintain a minimum altitude margin of 150 m above obstacles upstream of the runway.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q58 p.119](Questionnaire%20toutes%20branches%20VV.pdf#page=119) (score: 0.92)
+- PDF Answer: B
 
 ### Q221: Under which conditions do the strongest thermal and mechanical turbulences occur at noon? ^t50q221
 
@@ -4508,6 +5612,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q59 p.119](Questionnaire%20toutes%20branches%20VV.pdf#page=119) (score: 0.86)
+- PDF Answer: B
+
 ### Q222: When is water described as supercooled in a cloud? ^t50q222
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q222) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q222)
@@ -4526,6 +5636,12 @@
 Supercooled water is liquid water that remains in liquid state even when its temperature is below 0°C (down to approximately -40°C). This is possible because very pure droplets suspended in clouds lack freezing nuclei. Supercooled water is particularly dangerous for aviation because it freezes instantly on contact with the cold surface of an aircraft, producing rime or clear ice. It is encountered mainly in cumulus, altocumulus, and nimbostratus between 0°C and -20°C.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q60 p.119](Questionnaire%20toutes%20branches%20VV.pdf#page=119) (score: 0.72)
+- PDF Answer: A
 
 ### Q223: What is the width of the precipitation zone in a cold front? ^t50q223
 
@@ -4546,6 +5662,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q96 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 1.00)
+- PDF Answer: D
+
 ### Q224: How does visibility change when flying VFR from a cold air sector toward a warm front? ^t50q224
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q224) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q224)
@@ -4564,6 +5686,12 @@
 Advancing from cold air (polar air mass with good visibility) toward a warm front, the pilot encounters a progressive deterioration: cirrus thickens to cirrostratus, then altostratus, the ceiling lowers, and precipitation begins (rain or drizzle). Visibility deteriorates as the cloud layer thickens and precipitation becomes continuous. This gradual degradation gradient is a typical characteristic of warm front approach, in contrast to the cold front which abruptly deteriorates then rapidly improves conditions.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q97 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 0.94)
+- PDF Answer: C
 
 ### Q225: What is the width of the precipitation zone in a warm front? ^t50q225
 
@@ -4584,6 +5712,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q98 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 1.00)
+- PDF Answer: A
+
 ### Q226: How does the cloud base change when flying VFR from a cold air sector toward a warm front? ^t50q226
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q226) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q226)
@@ -4602,6 +5736,12 @@
 Approaching a warm front, the typical cloud sequence begins with high-altitude cirrus (very high base), followed by cirrostratus, altostratus, and then nimbostratus whose base can be very low (a few hundred metres). This ceiling drops gradually as the pilot approaches the front - a progressive warning that allows time to react, in contrast to the cold front which abruptly deteriorates conditions.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q99 p.127](Questionnaire%20toutes%20branches%20VV.pdf#page=127) (score: 0.94)
+- PDF Answer: D
 
 ### Q227: Which zone of an occlusion is most active? ^t50q227
 
@@ -4622,6 +5762,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q100 p.128](Questionnaire%20toutes%20branches%20VV.pdf#page=128) (score: 0.82)
+- PDF Answer: C
+
 ### Q228: When is the term "mist" used? ^t50q228
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q228) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q228)
@@ -4640,6 +5786,12 @@
 By international meteorological convention, mist is reported when visibility is between 1000 m and 8000 m due to the presence of fine water droplets or ice crystals in suspension. Below 1000 m visibility caused by condensed water vapour, the phenomenon is called fog. Above 8000 m, visibility is considered good. This distinction is important for METARs and VFR conditions.
 
 ---
+
+
+#### Source
+
+- Examen Blanc: [VV Q102 p.128](Questionnaire%20toutes%20branches%20VV.pdf#page=128) (score: 1.00)
+- PDF Answer: C
 
 ### Q229: How do temperature, dew point, and relative humidity behave in fog? ^t50q229
 
@@ -4660,6 +5812,13 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q104 p.129](Questionnaire%20toutes%20branches%20VV.pdf#page=129) (score: 0.65)
+- [QuizVDS Q46](../../Examen%20Blanc/QuizVDS/50%20-%20Meteorology.md#^q46): Answer B
+- PDF Answer: B
+
 ### Q230: What are the different stages of a thunderstorm cloud? ^t50q230
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q230) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q230)
@@ -4679,6 +5838,12 @@
 
 ---
 
+
+#### Source
+
+- Examen Blanc: [VV Q108 p.129](Questionnaire%20toutes%20branches%20VV.pdf#page=129) (score: 1.00)
+- PDF Answer: B
+
 ### Q231: What effect does icing have on a glider passing through cold precipitation? ^t50q231
 
 [DE](../SPL%20Exam%20Questions%20DE/50%20-%20Meteorologie.md#^t50q231) · [FR](../SPL%20Exam%20Questions%20FR/50%20-%20M%C3%A9t%C3%A9orologie.md#^t50q231)
@@ -4696,3 +5861,9 @@
 
 Icing is particularly critical for gliders: their performance depends on a very precise wing profile with thin margins. Ice accumulating on the leading edge deforms the aerofoil profile, increases drag and reduces lift, lowers the stall speed, and adds weight. These combined effects can make the aircraft uncontrollable within minutes. Unlike powered aircraft, gliders generally have no anti-icing systems, making them extremely vulnerable. Preventive avoidance is the only effective measure.
 
+
+
+#### Source
+
+- Examen Blanc: [VV Q114 p.131](Questionnaire%20toutes%20branches%20VV.pdf#page=131) (score: 0.80)
+- PDF Answer: D

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