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- A) Wind from NNE, 120 kt
- B) Wind from NNE, 70 kt
- C) Wind from SSW, 70 kt
- D) Wind from SSW, 120 kt
Correct: C)
Explanation: Wind barbs point in the direction the wind blows from, with speed indicated by barbs and pennants on the upwind end: a pennant = 50 kt, a long barb = 10 kt, a short barb = 5 kt. The symbol shows a wind from SSW with one pennant (50 kt) and two long barbs (20 kt), totalling 70 kt. Options A and B incorrectly identify the direction as NNE — wind barbs point FROM the wind source, not toward it. Option D overstates the speed to 120 kt.
Correct: C)
Explanation: Advection fog forms when warm, moist air is transported (advected) horizontally over a colder surface, cooling from below until it reaches its dew point and condensation occurs at ground level. 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.
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- A) Westerly wind situation
- B) Bise situation
- C) South Foehn situation
- D) North Foehn situation
Correct: C)
Explanation: The sketch depicts a South Foehn (Südföhn) situation, where a pressure gradient drives moist air from the south against the southern slopes of the Alps. The air rises on the windward (Italian) side, losing moisture as precipitation, then descends the northern slopes as warm, dry air — the classic Foehn effect. 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.
Correct: C)
Explanation: QFE is the atmospheric pressure measured at the aerodrome reference point. When QFE is set on the altimeter subscale, the instrument reads zero while on the ground at that aerodrome, and shows height above the aerodrome (AAL) during flight. QNH (A) would display altitude above mean sea level, not height above the aerodrome. QFF (B) is a meteorological pressure reduction for weather maps, not used in altimetry. QNE (D) is the standard pressure setting (1013.25 hPa) for flight level indication.
Correct: A)
Explanation: In the METAR group "29004KT 220V340": 290 is the wind direction in degrees (290° = WNW), 04 is the speed in knots, and "220V340" indicates the direction varies between 220° (SW) and 340° (NNW). Options B and C incorrectly interpret 290° as ESE — that would be approximately 110°–120°. Option D has the correct mean direction (WNW) but reverses the variability range to NE and SSE, which contradicts the 220V340 notation.
Correct: C)
Explanation: When an advancing cold front encounters warm, unstable air ahead of it in a European summer setting, the forced lifting triggers vigorous convection and the rapid vertical development of cumulonimbus (thunderstorm) clouds with heavy precipitation, lightning, and gusty winds. 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.
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- A) Gradual temperature increase, tailwind, isolated thunderstorms.
- B) Gradual temperature decrease, headwind, isolated thunderstorms.
- C) Gradual temperature increase, headwind, no thunderstorms.
- D) Gradual temperature decrease, tailwind, isolated thunderstorms.
Correct: B)
Explanation: Flying from LOWK (Klagenfurt, Austria) northward to EDDP (Leipzig, Germany), the aircraft moves into cooler air at higher latitudes, producing a gradual temperature decrease. The synoptic pattern on the chart indicates headwind conditions along this route and convective activity yielding isolated thunderstorms, particularly during summer. Option A wrongly predicts warming (heading north) and tailwind. Option C denies thunderstorm risk despite the synoptic instability shown. Option D correctly predicts cooling and thunderstorms but wrongly identifies a tailwind.
Correct: D)
Explanation: Cumulonimbus (Cb) clouds are massive convective clouds extending from near the surface to the tropopause, containing enormous quantities of water and ice sustained by powerful updrafts. They produce the heaviest showers, hail, and thunderstorms. 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.
Correct: B)
Explanation: At high altitude, the wind is approximately geostrophic, blowing parallel to the isobars with low pressure to the left and high pressure to the right in the Northern Hemisphere. With low pressure to the north and high to the south, the pressure gradient force points northward, and the Coriolis deflection turns the resulting wind to the right — producing a westward (east-to-west) flow. The balloon is therefore carried toward the west. Options A, C, and D misapply the Buys-Ballot law for this pressure configuration.
Correct: B)
Explanation: 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.
Correct: C)
Explanation: Advection fog forms when warm, moist air moves horizontally over a colder surface and is cooled from below to its dew point. This commonly occurs when maritime tropical air flows over cold ocean currents or cold land in early spring. 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.
Correct: A)
Explanation: Advection fog results from the horizontal transport (advection) of warm, moist air across a cold surface. The cold surface cools the air from below until it reaches its dew point, causing condensation at ground level. Option B describes mixing fog, where two air masses of different temperatures combine. 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.
Correct: B)
Explanation: As a cold front approaches, pressure falls ahead of it due to the pre-frontal trough. At the moment of frontal passage, pressure reaches its minimum, and immediately afterward it begins to rise sharply as cold, dense air moves in behind the front. This characteristic "V-shaped" pressure trace — a brief fall followed by a sustained rise — is the textbook pressure signature of cold front passage. Options A and D describe monotonic trends, while option C suggests no dynamic weather activity, none of which match frontal passage behaviour.
Correct: A)
Explanation: The polar front is the semi-permanent, quasi-continuous boundary zone separating warm subtropical air masses from cold polar air masses across the mid-latitudes, including Central Europe. It is the birthplace of extratropical cyclones. 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.
Correct: C)
Explanation: Summer high-pressure areas over Central Europe produce widely spaced isobars, indicating weak synoptic-scale pressure gradients and therefore light prevailing winds. In the absence of strong gradient winds, locally driven thermal circulations — valley breezes, sea breezes, slope winds — develop and dominate the airflow pattern. Option A contradicts itself (close isobars do not produce calm winds). Option B describes strong westerlies associated with low-pressure systems. Option D describes a cold northerly flow pattern, not typical of summer anticyclones.
Correct: B)
Explanation: In winter, high-pressure areas produce subsidence inversions that trap cold, moist air near the surface, creating widespread high fog (Hochnebel) and stratus layers, particularly in valley and basin locations across Central Europe. Winds are light due to the weak pressure gradient. Option A (frontal weather) is associated with low-pressure systems. Option C (squall lines and thunderstorms) requires convective instability absent in winter highs. Option D describes summer high-pressure conditions with thermal cumulus development, not the foggy, grey winter anticyclone.
Correct: B)
Explanation: The most dangerous airframe icing occurs between 0°C and -12°C because supercooled liquid water droplets are most abundant and largest in this temperature band. These droplets freeze on contact with aircraft surfaces, producing heavy ice accumulation. Below -20°C (D), most cloud water has already frozen into ice crystals that bounce off rather than adhering. 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.
Correct: A)
Explanation: Clear ice (also called glaze ice) forms when large supercooled water droplets strike an aircraft surface and flow back along it before freezing, creating a smooth, dense, transparent, and very heavy ice layer that closely conforms to the surface shape. It is the most dangerous type of airframe ice because it is difficult to detect and remove. Rime ice (D) forms from small droplets that freeze instantly on contact, trapping air and creating a rough, white, opaque deposit. 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.
Correct: A)
Explanation: 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.
Correct: D)
Explanation: The cumulus (initial/developing) stage of a thunderstorm is characterised exclusively by updrafts that build the cloud vertically from cumulus congestus toward cumulonimbus. No downdrafts or precipitation have yet developed. 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.
Correct: B)
Explanation: Intense showers and thunderstorms produce powerful downdrafts (microbursts and downbursts) driven by precipitation drag and evaporative cooling. When these downdrafts hit the ground they spread outward, generating dangerous low-level wind shear that can cause sudden airspeed loss on approach. Sea-breeze fronts (C) produce mild convergence, not heavy downdrafts. 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.
Correct: D)
Explanation: The surface weather chart (synoptic analysis chart) depicts observed mean sea-level pressure using isobars, identifies pressure centres (highs and lows) with their central pressures, and plots the positions of fronts (warm, cold, occluded, stationary) based on actual observations. A prognostic chart (B) shows forecast conditions, not current observations. A wind chart (C) displays wind vectors only. A hypsometric chart (A) shows the height of constant-pressure surfaces aloft, not MSL pressure or surface fronts.
Correct: C)
Explanation: Satellite images (visible, infrared, and water vapour channels) provide a synoptic overview of cloud cover distribution, cloud type estimation, and the identification of frontal lines by recognising characteristic cloud patterns. Turbulence and icing (A) cannot be directly measured by satellite — those require pilot reports or forecast models. 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.
Correct: C)
Explanation: ATIS (Automatic Terminal Information Service) broadcasts include operational aerodrome information such as the active runway, transition level, approach type in use, and relevant NOTAMs — none of which are encoded in a METAR. A METAR already contains precipitation types (A), visibility and cloud information (B), and wind speed including gusts (D). ATIS supplements the METAR with the operational data pilots need for arrival and departure.
Correct: C)
Explanation: Cumulus clouds are the visible markers of thermal convection: warm air rises from the surface, cools adiabatically to the dew point, and condenses, forming the flat-based, cauliflower-topped cloud that glider pilots use to locate thermals. Stratus (B) forms from broad, gentle lifting in stable air, not from thermals. 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.
Correct: B)
Explanation: 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.
Correct: C)
Explanation: The dry adiabatic lapse rate (DALR) is exactly 1.0°C per 100 m (or approximately 3°C per 1000 ft). This is the rate at which an unsaturated air parcel cools when rising (or warms when descending) purely due to adiabatic expansion or compression. Option A (0.6°C/100 m) is approximately the saturated adiabatic lapse rate. 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.
Correct: C)
Explanation: Conditional instability means the atmosphere is stable for unsaturated air but becomes unstable once air parcels are lifted to saturation. When triggered — by surface heating, orographic lift, or frontal forcing — this instability produces vigorous convection: towering cumulus and cumulonimbus clouds with isolated showers and thunderstorms. Clear skies (A) indicate absolute stability or dry conditions. Layered clouds with prolonged rain (B) characterise absolutely stable (stratiform) weather. Shallow mid-level cumulus (D) indicates limited instability insufficient for significant vertical development.
Correct: C)
Explanation: The figure MET-004 shows thin, wispy, high-altitude clouds with a delicate fibrous or streaky structure — the defining visual characteristics of cirrus clouds. Cirrus forms above approximately 6,000 m (FL200) and consists entirely of ice crystals, which produce its distinctive silky or hair-like appearance. Stratus (A) is a grey, featureless layer cloud at low altitude. Cumulus (B) has a well-defined, puffy vertical structure. Altocumulus (D) appears as white or grey patches or layers of rounded masses at mid-level.
Correct: C)
Explanation: Medium to large precipitation particles (raindrops, hailstones) need time to grow by collision-coalescence or the Bergeron ice-crystal process, and strong updrafts keep droplets and ice crystals suspended in the cloud long enough for this growth to occur. Without sufficient updraft strength, particles fall out before reaching significant size. An inversion layer (A) suppresses cloud growth and precipitation. 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.
Correct: B)
Explanation: On standard synoptic weather charts, a warm front is depicted as a line with semicircles pointing in the direction of movement (into the colder air mass). The referenced figure MET-005 shows symbol (2) matching this convention — semicircles on one side of the frontal line. A cold front (A) uses triangular barbs pointing in the direction of advance. 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.
Correct: C)
Explanation: The warm sector lies between the warm front and the cold front, containing the warmest, most homogeneous air. During summer, this air mass typically offers moderate to good visibility with scattered or broken cloud layers — flyable VFR conditions. Visibility below 1000 m with ground-covering cloud (A) is more typical of winter fog or orographic stratus. Heavy showers and thunderstorms (D) are characteristic of the cold front itself, not the warm sector. Few isolated high clouds (B) describe pre-frontal conditions well ahead of the system.
Correct: B)
Explanation: After a cold front passes, cold, clean polar air replaces the warm sector. This unstable air mass produces excellent visibility between showers, with convective cumulus clouds developing from surface heating and occasional rain or snow showers from cumulus congestus. Option A describes warm front approach conditions (lowering bases, continuous rain). 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.
Correct: D)
Explanation: A polar front low (extratropical cyclone) is steered by the upper-level airflow, which is closely approximated by the direction of the isobars in the warm sector — the warm sector wind effectively carries the entire system along. This is a more reliable steering rule than fixed seasonal directions. 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.
Correct: A)
Explanation: The classic pressure trace of a passing polar front low follows three phases: pressure falls as the warm front approaches (the low draws nearer), pressure holds relatively steady in the warm sector between the two fronts, and pressure rises sharply after the cold front passes as cold, dense air replaces the warm sector. Option B wrongly has pressure rising ahead of the warm front. Option C has pressure falling behind the cold front, contradicting the arrival of dense cold air. Option D reverses the entire pattern.
Correct: D)
Explanation: 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.
Correct: A)
Explanation: When cold air intrudes into the upper troposphere, it reduces the thickness of the atmospheric column (cold air is denser and occupies less vertical space), causing the heights of upper pressure surfaces to drop. This creates an upper-level low or trough. These cold-pool lows aloft are potent triggers for convective instability and often initiate cyclogenesis at the surface. 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.
Correct: C)
Explanation: Cold air advecting into the upper troposphere steepens the lapse rate (cold air aloft over relatively warmer air below), producing conditional or even absolute instability. This destabilisation triggers convection, generating showers and thunderstorms — especially when combined with surface moisture and daytime heating. 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.
Correct: D)
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.
Correct: B)
Explanation: In summer, anticyclones bring subsiding air that warms adiabatically, suppressing deep convection and producing clear to partly cloudy skies with perhaps a few fair-weather cumulus (Cu humilis) from daytime thermal heating. The overall character is settled, warm, and dry. Squall lines and thunderstorms (A) require convective instability not present in a well-established high. 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.
Correct: C)
Explanation: On the windward (Stau) side during Foehn, moist air is forced to rise over the mountain barrier, cooling adiabatically and producing dense layered clouds (stratus, nimbostratus), obscured mountain peaks, poor visibility, and moderate to heavy orographic precipitation. Option D describes the lee-side Foehn effect — warm, dry, gusty descending wind — which is the opposite side of the mountains. 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.
Correct: B)
Explanation: Weather radar detects precipitation directly by measuring the intensity of microwave energy backscattered from raindrops, snowflakes, and hail. Radar imagery shows the precise location, extent, and intensity of precipitation areas in near-real-time. A satellite picture (D) shows cloud cover but cannot directly distinguish precipitating from non-precipitating clouds. 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.
Correct: D)
Explanation: An inversion is a layer of the atmosphere where temperature increases with altitude, which is the reverse ("inversion") of the normal tropospheric lapse rate. Inversions are extremely stable and act as lids that suppress convection, trap pollution, and limit thermal development for glider pilots. Option B describes an isothermal layer (constant temperature). Option C describes the normal lapse rate. Option A is incorrect because atmospheric pressure always decreases with height, regardless of the temperature profile.
Correct: C)
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.
Correct: C)
Explanation: An occluded front is depicted on synoptic charts by a line combining both the cold front triangles and the warm front semicircles on the same side, representing the merger of the two fronts when the faster-moving cold front overtakes the warm front. Symbol (3) in figure MET-005 shows this combined symbology, identifying it as an occlusion. A warm front (A) uses only semicircles. A cold front (B) uses only triangles. A front aloft (D) has a distinct marking indicating the frontal surface does not reach the ground.
Correct: C)
Explanation: A stationary front is a boundary between two contrasting air masses — here polar and subtropical — that is not moving significantly in either direction. Neither the cold air nor the warm air is advancing. 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.
Correct: B)
Explanation: An active shower near an airfield indicates ongoing convective downdrafts and outflow boundaries that create severe, rapidly changing low-level wind shear — a critical hazard during takeoff and landing. The gust front from a nearby shower can change wind direction and speed dramatically within seconds. Cross-country flying below moderate Cu (A) involves normal soaring conditions. 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.
Correct: C)
Explanation: 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.
Correct: C)
Explanation: In METAR format, the descriptor "SH" (shower) is combined with the precipitation type "RA" (rain) to form "SHRA," which denotes moderate showers of rain. No intensity prefix means moderate. "+RA" (B) indicates heavy continuous rain, not a shower. "TS" (A) denotes a thunderstorm without specifying precipitation type. "+TSRA" (D) indicates a heavy thunderstorm with rain — a more severe phenomenon than a simple rain shower.
Correct: B)
Explanation: SIGMET (Significant Meteorological Information) warnings are issued for Flight Information Regions (FIRs) and Upper Information Regions (UIRs), which are standardised ICAO airspace blocks managed by specific ATC authorities. They warn of hazardous weather phenomena (severe turbulence, icing, volcanic ash, thunderstorms) within these defined airspace volumes. SIGMETs are not issued for individual airports (A) — those use AIRMETs or aerodrome warnings. They are not route-specific (C) or country-specific (D), as a single country may contain multiple FIRs.
