Meteorology
Atmosphere and weather systems
Understand ISA, pressure systems, fronts, thunderstorms, icing, wind shear, and fog. Know the standard atmosphere values: sea level 15 °C, 1013.25 hPa, lapse rate 1.98 °C/1 000 ft (≈2 °C/1 000 ft).
Key concepts
- Pressure: QNH (above MSL), QFE (above field), QNE (standard). Altimeter settings change with pressure - "high to low, look out below."
- Fronts: cold front = rapid, narrow, convective; warm front = slow, wide, stratiform.
- Thunderstorms: three stages (cumulus, mature, dissipating); hazards: hail, icing, wind shear, microburst.
- Icing: clear ice (large droplets, rapid), rime ice (small droplets, slower), mixed.
- Fog types: radiation, advection, frontal, upslope.
- Wind shear and microburst: avoid low-level flight near convective activity.
Traps
- Confusing QNH and QFE; forgetting that flying from high to low pressure without resetting the altimeter reads too high.
- Mixing clear vs rime ice conditions.
- Assuming warm fronts produce only benign weather.
- Confusing advection fog (warm moist air over cold surface) with radiation fog (clear night, calm).
Worked example / rule of thumb
Pressure altitude = indicated altitude + 30 ft per hPa below 1013. Rule of thumb: 1 hPa ≈ 30 ft. If QNH is 1003, add ~300 ft to indicated to get pressure altitude.
Standard lapse rate: temperature drops ~2 °C per 1 000 ft.