Calvus Cloud Species:Without Cirriform, Hairless

Get a full description of cumulonimbus calvus clouds, including pictures and images of their various characteristics, how to identify them, and more.

Cumulonimbus calvus praecipitatio (Cb cal pra)
Cumulonimbus calvus praecipitatio (Cb cal pra)

Identifying the calvuscloud species

A species of cumulonimbus cloud whose upper portion appears bald and cauliflower-like

The ‘calvus’ cloud species is one of only two species that’s associated with cumulonimbus clouds. No other cloud type besides a cumulonimbus cloud can receive a calvus classification. Translated from latin, meaning bald, a cloud that’s classified as cumulonimbus calvus can be best identified through the puffy and cumuliform appearance at the top of the cloud.

The proper cloud classification abbreviation for this cloud is ‘Cb cal’. The precursor to these clouds are usually cumulus congestus clouds, and can be differentiated through a darker base, thunder, lightning, precipitation, all of which are features of cumulonimbus clouds. Depending on the conditions, these clouds can morph from a cumulus congestus, to a cumulonimbus calvus, to a cumulonimbus capillatus incus (thunderstorm with an anvil cloud) within the matter of minutes.

Other cloud features and accessories that might be associated with these clouds include pileus (cap cloud), virga (evaporating rain strips), and praecipitatio (rainfall). On the rare occasion, a fire could assist with the formation of these clouds, which would give the cloud a classification of cumulonimbus calvus flammagenitus. Clouds identified as cumulonimbus calvus aren’t particularly common, and often might be difficult to classify if the cloud is right above you or if other clouds are obstructing your view.

Calvus and its cloud type

Calvus is used with the cloud type shown below. The main type identifies the broader cloud form, while this term adds a more precise classification.

Compare calvus with related cloud species

Use the defining shape, arrangement, associated cloud type, and full sky context before selecting the most appropriate term.

Calvus vs. capillatus

Both describe cumulonimbus tops. Calvus has a smoother, rounded upper portion, while capillatus has a clearly fibrous or hair-like top.

Illustration of calvus clouds
Calvus
Illustration of capillatus clouds
Capillatus

See a calvus cloud classification in action

Follow a real photograph through the visible clues that lead to a complete cloud classification.

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