Meteorology
What this paper tests
Meteorology covers atmospheric behaviour and the products you read: pressure and altimetry, stability and cloud, icing, thunderstorms, wind shear, fog and fronts, plus METAR/TAF decoding and tropical weather. In Indonesia, convection, the monsoon and haze dominate practical decision-making.
Core rules
- ISA: 15 °C and 1013.25 hPa at mean sea level, lapse rate 1.98 °C per 1000 ft up to the tropopause, pressure change of about 1 hPa per 30 ft.
- QNH on the subscale gives elevation on the ground; QFE gives height above the aerodrome; 1013.2 gives flight levels above the transition altitude.
- Unstable air gives cumuliform cloud, showers and good visibility between them; stable air gives stratiform cloud, drizzle and haze.
- Icing: clear ice from large supercooled drops in cumulus, rime from small drops in stratus; both alter aerofoil shape and add weight.
- Thunderstorms have cumulus, mature and dissipating stages; hazards are hail, lightning, microbursts, gust fronts, severe turbulence and icing. Give cells at least 20 nm lateral clearance.
- Fog types: radiation fog on clear, calm nights; advection fog over a cold surface with wind; upslope and precipitation fog.
- Tropical climate: the northwest monsoon (roughly December to March) brings the wet season, the southeast monsoon the drier season; the ITCZ and sea breezes generate afternoon cumulonimbus over the islands and the Bukit Barisan range.
Worked example
Decode 'WAAA 120300Z 30008KT 8000 -RA SCT018 27/25 Q1008': wind 300° at 8 kt, visibility 8 km, light rain, scattered cloud at 1800 ft, temperature 27 °C, dew point 25 °C, QNH 1008 hPa. With a spread of 2 °C, convective cloud base is about 2 × 400 = 800 ft AGL and the air is close to saturation, so expect further showers and low cloud en route.
Traps that cost marks
- Reading METAR wind direction as magnetic; METAR and TAF report degrees true.
- Using QFE where QNH is needed to derive aerodrome elevation.
- Confusing BR (mist, visibility 1000–5000 m) with FG (fog, below 1000 m).
- Assuming clear, calm nights avoid fog - they are exactly the radiation-fog recipe.