Cumulus clouds with great vertical extent form when which conditions prevail?

• A. Abundant moisture and unstable atmosphere
• B. High humidity and stable air
• C. Very dry air
• D. Light wind shear

Answer: (A)

Tall cumulus clouds with great vertical extent form when there is abundant moisture and an unstable atmosphere. Abundant moisture provides the water vapor needed to condense as air rises, while instability makes rising air parcels buoyant enough to continue ascending instead of leveling off. As the parcels rise and cool, condensation releases latent heat, which boosts their buoyancy and drives even more growth, producing towering clouds. If the air is stable, rising motions are suppressed and clouds stay shallow; very dry air limits the available moisture for cloud formation; humidity alone can’t create tall clouds without the buoyant energy from instability. Light wind shear can tilt or organize convection but isn’t the primary driver of deep vertical development.