Which cloud type is most commonly associated with lifting action and unstable, moist air?

• A. Cumulonimbus
• B. Stratus
• C. Cirrus
• D. Altostratus

Answer: (A)

Cumulonimbus clouds form where moist air is strongly lifted, usually by convection, fronts, or another source of instability. As warm air rises, it cools and the moisture condenses, allowing the cloud to grow tall with powerful updrafts. This vertical development signals unstable conditions and abundant moisture, often leading to thunderstorms. The other clouds reflect different atmospheric conditions: stratus are low, layered, and indicate stable air with little vertical motion; cirrus are high, wispy cirrus at upper levels; altostratus are mid-level sheets. So the presence of lifting, instability, and moisture points to cumulonimbus as the characteristic type.