FAA Commercial Pilot Airplane (CAX)WeatherMedium
A pilot is flying at 12,000 feet MSL and notices the formation of lenticular clouds over mountainous terrain. What atmospheric conditions are indicated by the presence of these clouds?
- ALow-level moisture, light winds, and developing advection fog.
- BA severe temperature inversion at the mountaintops.
- CUnstable air and localized convection.
- DStable air, strong winds, and the presence of mountain waves.
Show answer & explanationAnswer & explanation
Correct answer: D. Stable air, strong winds, and the presence of mountain waves.
Lenticular clouds are distinctive lens-shaped clouds that form in the troposphere, typically in stable air masses over mountainous regions. They are a strong indicator of mountain wave activity, where strong winds are blown across terrain, creating standing waves in the atmosphere. The air is stable, which allows for the smooth, wave-like flow.
Why the other options are wrong
- A. Incorrect. Advection fog forms at low levels with light winds, and lenticular clouds are a mid- to high-level phenomenon associated with strong winds.
- B. Incorrect. While an inversion can be present, the primary indicator for lenticular clouds is mountain wave activity, which requires stable air and strong winds.
- C. Incorrect. Unstable air and convection would lead to cumuliform clouds, not lenticular.
Lenticular Clouds
Lenticular clouds (Altocumulus Lenticularis) are distinctive lens-shaped clouds that form in stable air when strong winds blow over mountainous terrain, indicating the presence of mountain waves.
- Lens-shaped, often appear stationary.
- Form in stable air.
- Strong indicator of mountain waves.
- Associated with strong winds at altitude.
- Can be a sign of turbulence for aircraft.
Memory trick: Lenticular: Lens-like, Lofty, Linked to Waves.