Meteorology
What the exam tests
Meteorology covers pressure, wind, clouds, icing, thunderstorms, turbulence, visibility and Iranian local effects: Zagros mountain waves, Alborz lee waves, summer dust and winter fog. You must read METAR/TAF and apply QNH/QFE correctly.
Core rules
- ISA: 15°C at MSL, 1.98°C/1,000 ft lapse, 1013.25 hPa. Pressure decreases about 1 hPa per 27 ft near the surface.
- QNH sets aerodrome elevation on the altimeter; QFE reads height above the reference datum; flight levels use 1013.25.
- Thunderstorm hazards: microburst, hail, icing, lightning, wind shear. Avoid by 20 NM and do not fly beneath the anvil.
- Icing: clear ice from large supercooled drops in stratiform clouds; rime from small drops; use anti-ice before entering.
- Dust reduces visibility and damages engines; fog forms in calm, moist winter conditions.
Worked example
METAR OIII 121200Z 00000KT 3000 BR SCT020 08/07 Q1018. Aerodrome elevation is 3,962 ft. With QNH 1018, the altimeter at the apron should read 3,962 ft. If the pilot sets QFE, it should read zero. On departure, the 3,000 m visibility and mist require instrument or special VFR procedure unless the operator's minima allow otherwise. Reasoning: QNH is the only setting that makes the altimeter read elevation; mist is not fog, but visibility is below many VFR minima.
Traps
Using QFE for en-route levels; applying 27 ft/hPa at flight level (use standard pressure); assuming 'BR' means fog; ignoring mountain-wave turbulence downwind of the Alborz; reading TAF as a forecast for the exact hour rather than a period.