Correct: D)
Explanation: The saturated (moist) adiabatic lapse rate averages approximately 0.6 degrees C per 100 m. It is lower than the dry adiabatic lapse rate (1.0 degrees C per 100 m) because latent heat released during condensation partially offsets the cooling of the ascending air parcel. 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.
Correct: B)
Explanation: The subtropical high-pressure belt at approximately 30 degrees N and S latitude is a semi-permanent feature of the global atmospheric circulation, created by the descending branch of the Hadley cell. Warm air rising near the equator flows poleward aloft, cools, and subsides in the subtropics, forming persistent anticyclones over the oceans (e.g., the Azores High, the Pacific High). Option A (equatorial regions) is dominated by the low-pressure Intertropical Convergence Zone (ITCZ). 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.
Correct: B)
Explanation: ATIS (Automatic Terminal Information Service) is a continuous broadcast available on a dedicated frequency at equipped aerodromes, providing current weather observations, active runway, transition level, approach procedures, and relevant NOTAMs specific to that aerodrome. Pilots tune in to the ATIS frequency during flight to obtain up-to-date destination information. Option A (SIGMET) covers significant weather hazards across an entire FIR, not aerodrome-specific data. Option C (PIREP) contains pilot-reported weather conditions en route. Option D (VOLMET) broadcasts weather for multiple aerodromes but is less comprehensive than ATIS for a specific destination.
Correct: A)
Explanation: The cloud in figure MET-002 is cumulus, identifiable by its characteristic flat base (marking the condensation level) and vertically developed, cauliflower-like top with sharp white outlines against the blue sky. Cumulus clouds form through thermal convection and are the clouds most associated with soaring flight. Option B (cirrus) would appear as thin, wispy ice-crystal filaments at very high altitude. 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.
Correct: B)
Explanation: An air mass acquires its temperature and moisture properties from the surface conditions of its source region (e.g., polar continent, tropical ocean) and then modifies as it travels over different surfaces along its trajectory. Both the origin (which sets the initial character) and the path (which modifies it) are essential for classifying and forecasting air mass behaviour. Option A (wind speed and tropopause height) are dynamic properties, not defining characteristics. 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.
Correct: C)
Explanation: 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.
Correct: C)
Explanation: 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 MET-005 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.
Correct: C)
Explanation: In METAR codes, precipitation intensity is indicated by a '+' prefix (heavy) or '-' prefix (light); no prefix means moderate. Rain is coded 'RA'. Therefore heavy rain is '+RA' (written as '+RA' in the standard, shown in the options as '.+RA'). 'RA' alone (option B) means moderate rain. 'SHRA' (option D) means shower of rain (moderate). '+SHRA' (option A) means heavy shower of rain — a convective shower, not continuous heavy rain.
Correct: C)
Explanation: 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.
Correct: B)
Explanation: 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.
Correct: B)
Explanation: 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.
Correct: C)
Explanation: Blue thermals are thermals that extend to significant altitude but remain below the condensation level (dew point height), so no Cumulus clouds form — the sky appears clear (blue). They are invisible to glider pilots and require instruments or experience to exploit. Option D confuses thermals with cloud coverage statistics. Option B describes sink between Cu clouds. Option A describes clear-air turbulence (CAT) near thunderstorms, a different phenomenon.
Correct: C)
Explanation: The 'beginning of thermals' (Thermikbeginn) is the moment when thermal lift becomes sufficiently strong and deep (reaching at least 600 m AGL) for a glider to sustain flight and gain height — this is the practical definition. It does not require Cu cloud formation (option A), nor does it specify a fixed MSL altitude (option B). Option D adds an unnecessary cloud formation criterion to what is fundamentally an altitude threshold.
Correct: B)
Explanation: The trigger temperature is the minimum ground temperature that must be reached before thermals are strong enough to carry air parcels to the condensation level and form Cumulus clouds. It is found on a tephigram or skew-T diagram by tracing the dry adiabatic lapse rate from the surface intersection until it meets the temperature profile. Options A and C misstate it as a temperature reached aloft or a threshold for thunderstorm formation. Option D describes thunderstorm formation, not Cu formation.
Correct: C)
Explanation: Over-development (Überentwicklung) occurs when Cumulus clouds develop vertically beyond Cu congestus into rain-producing Cumulonimbus clouds, generating showers and thunderstorms. This typically happens in the afternoon when the atmosphere becomes increasingly unstable. Option A describes a change in thermal visibility. 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).
Correct: C)
Explanation: Shielding (Abschirmung) refers to a layer of high or mid-level cloud (such as Cirrostratus, Altostratus, or Altocumulus) that intercepts solar radiation before it reaches the ground, thus reducing or suppressing the surface heating required for thermal development. Option D describes cloud cover on a windward mountain slope. Option A describes the anvil of a Cb, not shielding. Option B describes sky coverage in oktas, which is unrelated.
Correct: A)
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.
Correct: C)
Explanation: At MSL under ISA conditions, the standard air density is 1.225 kg/m³. A cube with 1 m edges has a volume of 1 m³, so its mass is 1.225 kg. Option B (0.01225 kg) is off by a factor of 100, option D (0.1225 kg) by a factor of 10, and option A (12.25 kg) by a factor of 10 in the opposite direction. These represent common decimal-point errors.
Correct: D)
Explanation: The tropopause is the boundary layer separating the troposphere (where temperature decreases with altitude) from the stratosphere (where temperature is initially constant and then increases due to ozone absorption). It is not the layer above the troposphere (option C), nor the height where temperature starts to decrease (option A — that is the surface of the troposphere). Option B confuses the tropopause with the stratopause.
Correct: D)
Explanation: An inversion layer is an atmospheric layer in which temperature increases with increasing altitude, the reverse ('inversion') of the normal decrease. Inversions suppress vertical mixing and convection, trapping pollutants and inhibiting thermal development above them. Option B describes normal atmospheric conditions. Option C describes an isothermal layer. Option A describes a generic boundary without specifying the temperature gradient direction.
Correct: D)
Explanation: An isothermal layer is one in which temperature remains constant with increasing altitude — neither increasing (inversion, option A) nor decreasing (normal lapse rate, option C). Isothermal conditions are found, for example, in the lower stratosphere. Option B describes a generic atmospheric boundary layer, not a layer of constant temperature.
Correct: D)
Explanation: 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.
Correct: A)
Explanation: 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.
Correct: C)
Explanation: The spread (or dew-point spread) is the difference between the actual (dry-bulb) air temperature and the dew point temperature. A small spread indicates air close to saturation; when the spread reaches zero, condensation and fog or cloud formation occur. Option D is incorrect because dew point and condensation point are effectively the same. Option B describes relative humidity. Option A describes the saturation mixing ratio or absolute humidity capacity.
Correct: B)
Explanation: 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.
