ATPL(A) 050 MeteorologyRevision notes and practice questions

050 MeteorologyFree sample, 10 questions

1. 1Which of the following processes can cause the air temperature to decrease?
   1. Adiabatic cooling
   2. Expansion of air
   3. Radiation cooling
   4. Greenhouse effect
   5. Conduction cooling

   1. 1, 2, 3, 5.
   2. 1, 2, 5.
   3. 2, 3, 4, 5.
   4. 1, 3, 4, 5.
   Show the answer

   Answer A. Rising air expands as the surrounding pressure falls and cools adiabatically, so statements 1 and 2 describe the same cooling mechanism. At night the ground loses heat by long-wave radiation, and the air in contact with it then cools by conduction, which covers 3 and 5. The greenhouse effect is the odd one out: water vapour and CO2 absorb outgoing infrared and slow the cooling, so it warms rather than cools.

2. 2In the Northern Hemisphere, a pilot flying at 1000 ft AGL straight towards the centre of a LOW pressure area will most likely find the wind blowing from...

   1. right and behind.
   2. left and behind.
   3. right and ahead.
   4. about 45° to the right of directly ahead.
   Show the answer

   Answer B. Around a low in the northern hemisphere the air turns anticlockwise, and friction at 1000 ft adds a component across the isobars towards the centre. Flying straight at the centre, the circulation puts the wind on the aircraft's left, and the inflow towards the centre gives it a component from behind. Buys Ballot's law says the same thing: with your back to the wind, low pressure is on your left.

3. 3If a parcel of humid air is forced to rise from the ground in summer, (1) ___ may occur and unstable conditions for (2) ___ are created.

   1. (1) sublimation;
      (2) cloud formation.
   2. (1) condensation;
      (2) cloud dissipation.
   3. (1) sublimation;
      (2) cloud dissipation.
   4. (1) condensation;
      (2) cloud formation.
   Show the answer

   Answer D. Humid air forced to rise cools, reaches its dew point and the vapour condenses into cloud. Condensation releases latent heat, which warms the parcel relative to its surroundings and makes it more buoyant. That is how a moist summer air mass becomes unstable and builds convective cloud; sublimation plays no part in this.

4. 4Which option lists only main cloud genera that indicate an unstable atmosphere?

   1. Cirrocumulus, altocumulus, cumulus.
   2. Cumulonimbus, stratus, cirrocumulus.
   3. Cirrocumulus, altostratus, altocumulus.
   4. Cirrostratus, nimbostratus, stratus.
   Show the answer

   Answer A. Instability shows itself in heaped, convective cloud at whatever level it occurs: cumulus low down, altocumulus in the middle, cirrocumulus high up. The layered forms (stratus, altostratus, cirrostratus, nimbostratus) are the signature of stable air spreading out instead of rising, so any list containing one of them is wrong.

5. 5A trough is an area of (1) ______ causing widespread (2) ______, with (3) ______ along the line of the trough.

   1. (1) convergence, (2) lifting, (3) cumuliform clouds or squalls.
   2. (1) divergence, (2) descent, (3) clear skies and light winds.
   3. (1) divergence, (2) lifting, (3) cumuliform clouds or squalls.
   4. (1) convergence, (2) subsidence, (3) cumuliform clouds or squalls.
   Show the answer

   Answer A. In a trough the isobars bend out from a low, and the surface flow converges along its axis. Air that converges at low level has to go up, so the trough is a line of lifting, often marked by cumuliform cloud, showers or squalls. Divergence and descent are the features of a ridge or high, which gives clear skies and light winds.

6. 6Which statement about an aircraft being struck by lightning is true?

   1. The extent of the damage caused by the lightning strike is inversely proportional to the strength of the electric field the aircraft entered.
   2. The crew of an aircraft made of conductive material (e.g. metal) will generally suffer greater adverse effects from a lightning discharge than the crew of an aircraft made of non-conductive composite material.
   3. The flight crew might have temporary difficulties in determining the current attitude of flight.
   4. Although it flies through an electric field, the aircraft itself is not a charge carrier and therefore cannot initiate a lightning discharge.
   Show the answer

   Answer C. The flash of a nearby strike, especially at night, can dazzle the pilots for several seconds, making the instruments hard to read, so the crew may briefly struggle to determine the aircraft's attitude. That is why cockpit lights are turned fully up near thunderstorms. A metal airframe acts as a Faraday cage and protects the occupants better than a non-conductive one, not worse, and a charged aircraft can itself trigger a discharge.

7. 7Can TREND and TAF reports be found in scheduled HF VOLMETs and continuous VHF VOLMETs?

   1. These reports are prohibited in both HF and VHF VOLMETs.
   2. TRENDs are in both VOLMETs if available.
   3. TAFs are in scheduled VOLMETs only, if available.
   4. TAFs are contained in both whenever it is possible.
   Show the answer

   Answer B. VOLMET broadcasts carry the METARs or SPECIs of a group of aerodromes, each followed by its TREND forecast when one is issued, on both the scheduled HF and continuous VHF services. TAFs and SIGMETs may be added to HF VOLMET only when regional air navigation agreements provide for it, so they are not a standard content of both. Nothing prohibits trend forecasts in either broadcast.

8. 8In the standard atmosphere, what is the temperature lapse rate in the troposphere?

   1. -2°C / 1000 ft.
   2. -0.65°C / 1000 ft.
   3. -3°C / 1000 ft.
   4. -1.5°C / 1000 ft.
   Show the answer

   Answer A. ISA temperature falls by 6.5 °C per km, which is 1.98 °C per 1000 ft, rounded to 2 °C per 1000 ft, from +15 °C at mean sea level up to the tropopause at 36 090 ft. The tempting -0.65 °C is the same lapse rate expressed per 100 m, not per 1000 ft.

9. 9At FL370 the OAT is -45°C. What is the ISA deviation?

   1. -11.5°C
   2. +14°C
   3. -14°C
   4. +11.5°C
   Show the answer

   Answer D. The ISA tropopause is at 36 090 ft, so FL370 is already in the lower stratosphere where the standard temperature is constant at -56.5 °C. The deviation is -45 - (-56.5) = +11.5 °C. Extrapolating the 2 °C per 1000 ft lapse rate to FL370 gives -59 °C and the +14 trap.

10. 10In which of the following changes of state is latent heat absorbed?
    1. Evaporation
    2. Condensation
    3. Sublimation
    4. Deposition
    5. Freezing
    6. Melting

    1. 1, 3, 6.
    2. 2, 4, 6.
    3. 1, 2, 4.
    4. 2, 4, 5.
    Show the answer

    Answer A. Evaporation, sublimation and melting all move water to a more energetic state, so they absorb latent heat and cool their surroundings. Condensation, deposition and freezing are the reverse changes and release that heat. Any option containing 2, 4 or 5 therefore mixes in a heat-releasing process.