Meteorology
Core concepts
Study the atmosphere's stability, lapse rates, humidity, and how they produce clouds, precipitation and turbulence. Know pressure systems, fronts and their associated weather, the standard atmosphere, altimeter setting errors, and the formation of icing, fog, thunderstorms and wind shear. Understand METAR and TAF decoding, trend forecasts, and the meaning of QNH, QFE and standard pressure.
Traps
Examiners test false altimeter logic: flying from high to low pressure without resetting makes the altimeter read high while the aircraft is lower than indicated. Warm front versus cold front cloud sequences and slope are frequent. Also distinguish radiation fog (clear, calm night) from advection fog (moist air over a cold surface with wind), and remember that carburettor icing can occur at temperatures well above freezing.
Worked example
QNH at departure 1020 hPa, at destination 1000 hPa. Rule of thumb: 1 hPa is about 30 ft near sea level, so a 20 hPa fall means roughly 600 ft of true altitude error if the subscale is not updated. If you keep the old setting, the altimeter over-reads and terrain clearance is less than shown. Reset the subscale at each pressure change and on transition altitude.
Exam technique
Read METAR groups in order: wind, visibility, weather, cloud, temperature, pressure. Convert units carefully and check whether the question asks for indicated or true altitude.