Cumulonimbus capillatus
species of Cumulonimbus

Cumulonimbus characterized by an upper portion having cirriform parts of clearly fibrous or striated structure, frequently in the shape of an anvil (Cumulonimbus capillatus incus), a plume or a vast more or less disorderly mass of hair. In very cold air masses the fibrous structure very often extends virtually thoughout the cloud.

Cumulonimbus capillatus is usually accompanied by a shower or by a thunderstorm, often with squalls and sometimes with hail; it frequently produces very distinct virga.