When warm, moist, stable air flows upslope, it tends to produce which type of clouds?

• A. Stratus type clouds
• B. Cumulus clouds with vertical development
• C. Cirrus high clouds
• D. Altostratus clouds

Answer: (A)

Upslope lift in warm, moist, stable air tends to produce a low, flat cloud deck. Because the air is stable, it rises only gently as it moves up the slope, so it cools to its dew point at low levels and condenses into layered, sheet-like clouds. This is characteristic of stratus clouds, which form a continuous, gray covering rather than tall, puffy towers. Cirrus would require high, icy clouds formed far above in drier air; cumulus needs unstable air with strong updrafts causing vertical development; altostratus forms at mid levels under different lifting conditions, not the shallow upslope flow described.