ATPL Meteorology – Summary Notes
1. Atmosphere Composition & Structure
Composition: Nitrogen 78%, Oxygen 21%, Argon 0.9%, CO2 0.04%, variable water vapour.
Layers: Troposphere, Stratosphere, Mesosphere, Thermosphere.
2. Temperature & Stability
DALR: 3°C/1000ft
SALR: 1.5°C/1000ft
Stable: ELR < SALR
Unstable: ELR > DALR
3. Pressure & Wind
Standard pressure: 1013.25 hPa.
Wind controlled by pressure gradient force, Coriolis and friction.
4. Humidity & Cloud Formation
Relative humidity, dew point, absolute humidity.
Clouds form by convection, frontal lifting, orographic lifting, mixing and cooling.
5. Cloud Types
Low: St, Sc, Cu
Medium: As, Ac
High: Ci, Cs, Cc
Vertical: Cb
6. Fronts
Warm front: stratiform clouds, steady rain.
Cold front: cumuliform clouds, showers, storms.
Occlusion: complex structure, widespread rain.
7. Air Masses
mT, cT, mP, cP – properties depend on source region.
8. Icing
Rime, clear and mixed ice between 0 and -20°C.
9. Turbulence
Mechanical, thermal, frontal, CAT near jet streams.
10. Thunderstorms
Requirements: moisture, instability, lift.
Stages: cumulus, mature, dissipating.
11. Fog
Radiation, advection, hill, steam, frontal.
12. Jet Streams
Near tropopause, strongest in winter, west to east flow.
13. Reports
METAR: actual weather.
TAF: forecast.
SIGMET: hazardous phenomena.
14. ICAO Standard Atmosphere
Sea level temp +15°C, pressure 1013.25 hPa.