Meteorology
Core concepts
Meteorology covers the atmosphere, pressure systems, wind, clouds, precipitation, visibility, icing, thunderstorms, and the interpretation of METAR, TAF, and significant weather charts. Know the standard atmosphere, how pressure and temperature vary with altitude, the formation of fronts, and the hazards associated with each cloud type. Understand QNH, QFE, and QNE and how they are used in altimetry.
Traps to watch
A classic trap is the relationship between pressure and altimeter setting: flying from high to low pressure without adjusting the subscale causes the aircraft to be lower than indicated ("high to low, look out below"). Another is the distinction between advection and radiation fog, and the conditions that favour each. Questions on thunderstorms test knowledge of the three stages and the hazard of microbursts and wind shear on approach. Icing questions test the temperature range most favourable for airframe icing (roughly 0 to −20 °C) and the danger of freezing rain.
Worked example
Departing a high-pressure area and flying toward a low, with the altimeter unchanged, true altitude decreases. If the pressure difference is 4 hPa, the aircraft is about 120 ft lower than indicated (approximately 30 ft per hPa).
Rule of thumb
"High to low, look out below; low to high, plenty of sky." Always update the altimeter setting en route.