1.2.3.3. Pileus cloud caps

  • 9 months ago
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  • Author: SW101

Often, a white wispy cloud cap forms above rapidly rising updraft – a pileus cloud. It forms as moist, but stable air above a rapidly rising updraft is pushed upward, causing the water to condense. It is a short-lived cloud, which either fades or is overtaken by the rising updraft, then forming a wispy collar cloud, called a velum cloud.

Stage 1: rising updraft still below the stable layer of moist air aloft.

Stage 2: rising updraft pushes the stable layer of moist air upwards, causing it to condense and forming the pileus cloud (cap).

Stage 3: rising updraft punches through the pileus cloud cap, forming a velum cloud.

Pileus clouds are most often found above rapidly growing Cumulus congestus and Cumulonimbus calvus clouds.

Fun fact: pileus clouds can be found above other types of rapidly rising updrafts such as volcanic eruption columns and nuclear explosions.

On to examples!