Meteorology
Weather essentials
Know the standard atmosphere, pressure systems, and how temperature and dewpoint relate to cloud and fog. Understand stability: unstable air gives cumuliform cloud and showers; stable air gives stratiform cloud and steady precipitation. Learn the cloud types and their typical bases, and the difference between a cold front (fast, showery, gusty) and a warm front (slow, steady, low cloud).
Wind and local effects
Helicopters are sensitive to wind, gusts and turbulence. Know the wind triangle and how to estimate crosswind and headwind components. Local effects matter: valley winds, sea breezes, and mechanical turbulence near buildings and trees. Mountain waves and rotors are hazardous. In Brazil, convective activity and thunderstorms are frequent in summer; know the hazards of hail, lightning, downbursts and microbursts.
Traps
Questions give a temperature/dewpoint spread and ask about fog risk (a small spread means high risk). Others confuse QNH with QFE, or ask which way wind veers (clockwise) and backs (anticlockwise). Watch for items on icing - carburettor icing can occur at temperatures well above freezing.
Worked example
If the temperature is 20 °C and dewpoint 18 °C, the spread is 2 °C: expect fog or low cloud if the air cools slightly, so plan for reduced visibility.