Cumulonimbus

Definition

A genus of heavy, dense cloud of considerable vertical extent, in the form of a mountain or huge tower, whose upper part is at least partly glaciated, often with a smooth, fibrous or striated anvil shape on top.

Field note

Cumulonimbus is the only genus that routinely produces hail, lightning, damaging gusts and tornadoes. The mature stage is the only stage with a strong updraught and a strong downdraught at the same time.

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Cumulonimbus: the one cloud that can hurt you

Cumulonimbus is the only cloud genus that routinely produces hail, lightning, damaging gusts and tornadoes, and it is the only one where your observation practice has to include a decision about where to stand. It is a deep convective tower with an ice-crystal top, and it is genuinely different in kind from everything else in this atlas.

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Related terms

• Cumulus · Cumulus
• Virga · virga
• Mamma (mammatus) · mamma
• Incus · incus
• Praecipitatio · praecipitatio
• Tuba · tuba