Meteorology for Glider Pilots
The atmosphere and lift sources
Glider flying depends on vertical motion: thermals, ridge lift, wave, and convergence. Understand the lapse rate (dry adiabatic ~3 °C per 1,000 ft, saturated less), stability, and how an inversion caps thermals. Know the convective condensation level, cloud base estimation, and the difference between cumulus (good thermal markers) and overdevelopment into cumulonimbus (dangerous).
Synoptic and local effects
- Air masses: cold unstable air gives strong thermals and showers; warm stable air gives weak lift and haze.
- Fronts: a cold front brings squall lines, wind shifts, and rapid Cu development.
- Sea breeze and anabatic/katabatic flows modify local lift.
- Lee waves produce strong sink and turbulence on the downwind side; rotor zones are hazardous.
- Wind shear and gradient: surface wind differs from wind at height; always consider the wind gradient on approach.
Traps
Confusing the dry and saturated adiabatic lapse rates, or assuming cloud base equals the condensation level without allowing for temperature and dewpoint spread. Another trap: treating a forecast as certain - glider questions often test whether you can identify an unstable profile and the risk of overdevelopment.
Worked example
Surface temperature 24 °C, dewpoint 8 °C, spread 16 °C. Rule of thumb: cloud base ≈ 400 ft per 1 °C of spread ≈ 6,400 ft above ground (dry adiabatic approach: 16 °C / 3 °C per 1,000 ft ≈ 5,300 ft; the 400-ft rule is a rougher estimate). Treat the result as an estimate and check the actual sounding.