Certified Flight Instructor - Flight Instructor Airplane Practice Exam

If clouds form as a result of very stable, moist air being forced to ascend a mountain slope, the clouds will be:

1. Cirrus type with no vertical development or turbulence.

2. Cumulonimbus with considerable vertical development and heavy rains.

3. Stratus type with little vertical development and little or no turbulence.

The correct answer is: Stratus type with little vertical development and little or no turbulence.

When very stable, moist air is forced to ascend a mountain slope, the resulting clouds typically exhibit characteristics associated with stratus type clouds. These clouds form when the air mass is stable, meaning that the vertical movement of air is limited. As the air rises along the slope, it cools at a slower rate due to its stability, leading to widespread cloud formation without significant vertical development. Stratus clouds are generally characterized by their uniform gray appearance and can cover large areas, often resulting in overcast conditions. Since the air remains stable and relatively moist, the turbulence is minimal, contributing to the smooth, layered look of stratus clouds. Other cloud types like cirrus, which are high, wispy, and typically lack the moisture needed for precipitation, do not fit this scenario. Cumulonimbus clouds, on the other hand, signify strong instability and are associated with heavy vertical development and turbulence, leading to thunderstorms and heavy rainfall, which would not occur under stable air conditions. Thus, the formation of stratus clouds is the most accurate representation of what happens when very stable, moist air ascends a mountain slope.