The pyrocumulonimbus cloud (pyroCb) is a type of cumulus cloud formed above a source of heat such as a wildfire and may sometimes even extinguish the fire that formed it. It is the most extreme manifestation of pyrocumulus. According to the American Meteorological Society’s Glossary of Meteorology, a pyrocumulus is "a cumulus cloud formed by a rising thermal from a fire, or enhanced by buoyant plume emissions from an industrial combustion process."[1] Analogous to the meteorological distinction between cumulus and cumulonimbus, the pyrocumulonimbus is a fire-aided or –caused convective cloud but with considerable vertical development. The pyroCb reaches the upper troposphere or even lower stratosphere and may involve precipitation (although usually light), hail, lightning, extreme low-level winds, and in some cases even tornadoes [2]. The pyroCb was named following the discovery that extreme manifestations of this pyroconvection caused direct injection of large abundances of smoke into the lower stratosphere [3][4]
Alternate spellings and abbreviations for pyrocumulonimbus that may be found in the literature include pyro-cumulonimbus, pyro-cb, pyro-Cb and pyrocb. The World Meteorological Organization doesn't recognize pyrocumulonimbus as a distinct cloud type, but classifies it simply as cumulonimbus.
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Atmospheric convection