Cumulonimbus flammagenitus (cloud) on the fujita scale, the first confirmed violent fire tornado. The tornado and associated fire killed 4 people and injured 492. Cumulonimbus flammagenitus (cloud) The cumulonimbus flammagenitus cloud (CbFg) is a type of cumulonimbus cloud that forms 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 a flammagenitus cloud. According to the American Meteorological Society’s Glossary of Meteorology, a flammagenitus is "a cumulus cloud formed by a rising thermal from a fire, or enhanced by buoyant plume emissions from an industrial combustion process."
Cloud of a squall line or thunderstorm outflow. A large arcus formation can have the appearance of a dark menacing arch. Several new supplementary features have been formally recognized by the World Meteorological Organization (WMO). The feature "fluctus" can form under conditions of strong atmospheric wind shear when a stratocumulus, altocumulus, or cirrus cloud breaks into regularly spaced crests. This variant is sometimes known informally as a Kelvin–Helmholtz (wave) cloud. This phenomenon has also been observed in cloud formations over other planets and even in the sun's atmosphere. Another highly disturbed but more chaotic wave-like cloud feature associated with stratocumulus or