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 physics air containing invisible water vapor to rise and cool to its dew point, the temperature at which the air becomes saturated. The main mechanism behind this process is adiabatic cooling. Atmospheric pressure decreases with altitude, so the rising air expands in a process that expends energy and causes the air to cool, which makes water vapor condense into cloud. Water vapor in saturated air is normally attracted to condensation nuclei such as dust and salt particles that are small enough to be held aloft by normal circulation of the air. The water droplets in a cloud have a normal radius