Meteorology - Atmosphere, Hazards and Reports
The atmosphere and pressure
Know the ISA: sea level 15 °C and 1013.25 hPa with a lapse rate of 2 °C per 1,000 ft up to the tropopause. Pressure systems drive the wind; surface friction slows it and causes it to back, while the geostrophic wind flows parallel to the isobars aloft. Learn the local effects relevant to the Gulf: strong shamal winds raising dust and sand, sea breezes, and widespread haze reducing visibility.
Weather and hazards
Organise cloud knowledge by stability - cumuliform from unstable air, stratiform from stable air. Understand icing (clear ice in freezing rain, rime in stratus), the thunderstorm life cycle of cumulus, mature and dissipating stages with its gust front and microburst risk, and the formation of radiation and advection fog. The tropopause marks the top of most weather.
Interpreting reports
Practise decoding METAR and TAF: wind direction, speed and gusts, visibility, present weather, cloud amount and base, temperature, dew point, QNH and trend. Be able to convert between QNH, QFE and flight levels and to estimate the freezing level from the temperature profile.
Common traps
Reading cloud base in metres when it is given in feet; ignoring the dew-point spread; and forgetting that QNH is mean-sea-level pressure, not aerodrome pressure.
Worked example
A METAR gives temperature 30 °C and dew point 18 °C. The spread is 12 °C, so convective cloud base is roughly 12 × 400 = 4,800 ft above ground, and fog is unlikely while the spread stays this wide.