Private Pilot Private Exam

Crests of standing mountain waves may be marked by stationary, lens-shaped clouds known as...

1. Cumulus clouds

2. Lenticular clouds

3. Stratus clouds

4. Standing lenticular clouds

The correct answer is: Standing lenticular clouds

The correct answer refers specifically to "standing lenticular clouds," which is a term used to describe clouds that form in a lens shape and remain stationary, typically appearing over mountain ranges. These clouds are formed when moist air flows over mountains, creating turbulence and lifting the air to a point where it cools and condenses into these distinctive, smooth-edged cloud formations. These clouds can provide important visual indicators of mountain wave activity, which pilots should be aware of, as they indicate the presence of potential turbulence in the vicinity. The term "standing" is particularly relevant, as it highlights the fact that these clouds do not move with the wind but instead remain in place as air continues to flow over the mountains. Other cloud types mentioned, such as cumulus, stratus, and even simply lenticular clouds, do not fully capture this specific characteristic of remaining stationary in relation to the terrain. Cumulus clouds are puffy and generally form in fair weather, whereas stratus clouds are flat and layered, typically associated with overcast skies. While lenticular clouds do describe the lens shape, the additional descriptor "standing lenticular" emphasizes the phenomenon of being anchored or fixed in position relative to mountain waves.