FAA Private Pilot Airplane (PAR)Weather Theory and ServicesEasy
A pilot is briefed that the atmosphere along the route is very stable, with a strong temperature inversion near the surface. Which cloud type and flight condition should the pilot most likely expect?
- ATowering cumulus clouds with strong updrafts and moderate turbulence
- BWidely scattered cumulus clouds with excellent visibility and light chop
- CStratiform clouds with smooth air but possible reduced visibility in haze or smoke
- DCumulonimbus clouds with hail and severe turbulence
Show answer & explanationAnswer & explanation
Correct answer: C. Stratiform clouds with smooth air but possible reduced visibility in haze or smoke
A stable atmosphere suppresses vertical motion, favoring flat, layered (stratiform) clouds and smooth flight, but it also traps smoke, haze, and moisture near the surface, reducing visibility. Unstable air, by contrast, produces cumulus buildups and turbulence.
Why the other options are wrong
- A. Towering cumulus and turbulence are signs of instability, not stability.
- B. Good visibility with cumulus is more typical of an unstable, well-mixed atmosphere.
- D. Cumulonimbus and hail require strong instability and vertical development.
Stable Atmosphere Characteristics
A stable atmosphere resists vertical air movement, producing smooth flight conditions, stratiform clouds, and often poor surface visibility due to trapped moisture, smoke, or haze.
- Stable air = smooth flight, stratus/fog, poor visibility near surface
- Unstable air = cumulus buildups, turbulence, showers
- Inversions often mark the top of stable layers
Memory trick: Stable = Still & Smooth, Unstable = Up & Umbrella clouds