Certified Flight Instructor - Flight Instructor Airplane Practice Exam

What type of air stability typically leads to the development of stratus clouds?

1. Unstable warm air.

2. Stable, moist air.

3. High altitude winds.

The correct answer is: Stable, moist air.

The development of stratus clouds is primarily associated with stable, moist air. In meteorology, stable air occurs when the atmospheric conditions inhibit vertical motion, leading to the gradual accumulation of moisture in the lower layers of the atmosphere. When moist, stable air is present, it tends to spread out horizontally rather than rising, which is essential for the formation of stratus clouds. As this moist air settles, it cools and condenses, forming a layer of clouds that can cover large areas, often resulting in overcast skies with low cloud bases. Stratus clouds are typically uniform and can produce drizzle or light rain, but they are not associated with significant turbulence or severe weather, as they form in stable conditions. This characteristic makes them distinct from clouds associated with unstable air, which tend to be more vertical in structure, like cumulus or cumulonimbus clouds. The other options, while related to atmospheric conditions, do not directly lead to the formation of stratus clouds. Unstable warm air encourages vertical development, leading to cumuliform clouds, and high altitude winds pertain more to the movement of air masses rather than the conditions necessary for stratus cloud formation.