Aviation Meteorology
What this domain tests
The NCAA PPL meteorology paper checks whether you can take raw weather information - a METAR, a TAF, a forecast, a pressure setting - and turn it into a decision about a light aircraft in Nigerian airspace. Expect pressure and altimetry, temperature and density altitude, stability, cloud and visibility, winds, icing and thunderstorms, plus decoding of ICAO-coded reports.
The standard atmosphere and altimetry
- ISA sea level: 15 °C, 1013.25 hPa, lapse rate about 2 °C per 1,000 ft.
- QNH on the subscale gives altitude above mean sea level. QFE gives height above the aerodrome reference point - the altimeter reads zero on the ground.
- Flying from high pressure to low pressure, or warm air to cold air, without resetting the subscale makes the altimeter over-read: the aircraft is lower than shown. "High to low, look out below."
Density, stability and cloud
Pressure altitude corrected for non-standard temperature is density altitude. Hot afternoons plus a high-elevation aerodrome cut lift, lengthen the take-off run and flatten the climb. Unstable air produces cumuliform cloud, turbulence and showers; stable air gives stratiform cloud, haze and steady drizzle. Estimate convective cloud base from the temperature/dewpoint spread at roughly 400 ft per 1 °C.
Nigerian weather patterns
Seasonal movement of the ITCZ drives the two seasons. December–February brings harmattan dust haze from the north-east: sky may be almost clear while visibility drops to a few kilometres. The rainy season brings afternoon and evening thunderstorms, squall lines and heavy rain across the south.
Worked example
"DNKN 121200Z 07008KT 4000 HZ SCT010 32/22 Q1010" decodes as: wind 070° at 8 kt; visibility 4,000 m; haze; scattered cloud base 1,000 ft above aerodrome; temperature 32 °C, dewpoint 22 °C; QNH 1010 hPa. Spread is 10 °C, so expect cumulus bases near 4,000 ft - consistent with the reported SCT010. Set 1010 hPa when joining the circuit; 4 km visibility is workable for a PPL VFR flight but demands a decision on whether the haze is closing in.
Traps that cost marks
Mixing QFE and QNH values, forgetting that cloud height in METARs is above aerodrome level, and treating "clear sky, poor visibility" harmattan as no weather at all.