Meteorology
Meteorology
This domain covers the atmosphere, pressure, temperature, wind, clouds, precipitation, visibility, fronts, thunderstorms, icing and aviation forecasts. Kenya-specific weather includes the ITCZ, monsoon flows, Lake Victoria breezes and afternoon convection.
Core rules
- ISA: sea-level temperature 15°C, lapse rate about 1.98°C per 1,000 ft, sea-level pressure 1013.25 hPa.
- Pressure decreases about 1 hPa per 30 ft near the surface. QNH is the altimeter setting that gives elevation at the aerodrome.
- Cloud types indicate stability: stratiform cloud suggests stable air; cumuliform cloud and CBs suggest instability, turbulence and icing.
- METAR is current weather; TAF is forecast. Know wind, visibility, cloud, temperature/dew point, QNH and trend groups.
Worked example
Decode: HKJK 121200Z 09012KT 9999 SCT025 28/17 Q1015 NOSIG. Day 12, time 1200 UTC; wind 090° true at 12 kt; visibility 10 km or more; scattered cloud at 2,500 ft AGL; temperature 28°C, dew point 17°C; QNH 1015 hPa; no significant change expected. The reasoning is to read groups in the standard METAR order.
Traps
9999 means 10 km or more, not 9,999 m. Q1015 is QNH in hPa. SCT025 is 2,500 ft AGL. Do not confuse mist and fog by cause; use the reported visibility. CBs imply icing, turbulence and lightning.