Flammagenitus Cloud: Pyrocumulus, Caused From Fire

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Definition: A fire-caused cumulus or cumulonimbus cloud better known as a pyrocumulus cloud

Description & Characteristics. With flamma translated from latin meaning flame and genitus translated from latin mean created from, the ‘flammaagenitus’ cloud formation is found in convective cloud types, specifically cumulus or cumulonimbus, and describe a cloud that forms from a natural source of heat such as wildfires and volcanoes. The proper cloud classification abbreviation for this cloud is ‘Cb flgen’ and ‘Cu flgen’.

When a fire is burning on the ground, rising warm air has the potential to carry water vapor up into the atmosphere which can turn into clouds: cumulus, cumulus congestus, and sometimes even cumulonimbus clouds. These clouds that are created can include cloud species and features such as cap clouds (pileus cloud accessory), and anvil clouds (incus cloud feature).

On more rare occurrences, precipitation and lightning can occur with these clouds. Unfortunately, this can build the risk for the fire to grow through either the increased wind caused by the precipitation downdraft as well as new lightning-caused fires, both risks that firefighters must take into consideration as they perform their duties.

Cumulus congestus flammagenitus (Cu con flgen)
Cumulus congestus flammagenitus (Cu con flgen)
Cumulonimbus calvus pileus flammagenitus (Cu cal pil flgen)
A photograph of a cumulus congestus flammagenitus cloud (Cu con flgen) over a forest landscape

Flammagenitus Cloud Types

The flammagenitus cloud is associated with two cloud types: cumulonimbus and cumulus.

A graphical illustration of a cumulonimbus flammagenitus cloud

Cumulonimbus (Cb)


A graphical illustration of a cumulus flammagenitus cloud

Cumulus (Cu)

Low, puffy, fair-weather