If overrunning air is dry, which clouds are most likely present along a warm front?

If overrunning air is dry, which clouds are most likely present along a warm front?

• A. Cumulonimbus
• B. Stratus
• C. Only middle or high clouds
• D. Cirrus

Answer: (C)

When warm air overruns cooler air at a warm front, the altitude of condensation depends on how moist the overrunning air is. If that air is dry, saturation happens higher up in the atmosphere, so low-level clouds don’t form as readily. Instead you’ll see cloud decks composed of mid- and high-level clouds, such as altostratus and cirrus-type clouds, rather than low stratus or vertically developed clouds fueled by abundant moisture and instability. Cumulonimbus require strong lifting and ample moisture, which isn’t present here, and low stratus would need more moisture near the surface, which isn’t available. So the most likely scenario along a dry overrunning warm front is a deck of only middle or high clouds.

When warm air overruns cooler air at a warm front, the altitude of condensation depends on how moist the overrunning air is. If that air is dry, saturation happens higher up in the atmosphere, so low-level clouds don’t form as readily. Instead you’ll see cloud decks composed of mid- and high-level clouds, such as altostratus and cirrus-type clouds, rather than low stratus or vertically developed clouds fueled by abundant moisture and instability. Cumulonimbus require strong lifting and ample moisture, which isn’t present here, and low stratus would need more moisture near the surface, which isn’t available. So the most likely scenario along a dry overrunning warm front is a deck of only middle or high clouds.