From Glossary of Meteorology


An extreme manifestation of a pyrocumulus (pyroCu) cloud, generated by the heat of a wildfire, that often rises to the upper troposphere or lower stratosphere. Often abbreviated “pyroCb.” The pyroCb is distinctive owing to the presence of smoke, giving the cloud an off-white color and peculiar signatures at certain infrared wavelengths. The distinguishing characteristics of pyroCb, as opposed to pyroCu, are production of lightning, thunder, or hail or a fibrous or diffuse upper portion. The discovery of hemisphere-scale stratospheric smoke plumes traceable to pyroCbs reveals their buoyant energy and potential to inject smoke into the lower stratosphere. A pyrocumulonimbus cloud is also known as a pyrocumulonimbus flammagenitus cloud (CbFg).

World Meteorological Organization, 2017. International Cloud Atlas. Available at

Term edited 1 March 2021

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