A fire whirl, also colloquially known as a fire devil, fire
tornado,or fire twister is a whirlwind induced by a fire and often made up of
flame or ash. Fire whirls may occur when intense rising heat and turbulent wind
conditions combine to form whirling eddies of air. These eddies can contract
into a tornado-like structure that sucks in burning debris and combustible gases.
Rarely, however, do fire whirls grow to become actual tornadoes, which are
violently rotating vortices connecting the surface to a cumuliform such as
pyrocumulus cloud base. A fire whirl consists of a core the part that is
actually on fire and an invisible core of a fire whirl can reach up to 2,000 °F
hot enough to potentially reignite ashes sucked up from the ground. Often, fire
whirls are created when a wildfire or firestorm creates its own wind, which can
turn into a spinning vortex of flame.
Combustible, carbon-rich gases released by burning
vegetation on the ground are fuel for most fire whirls. When sucked up by a
whirl of air, this unburned gas travels up the core until it reaches a region
where there is enough fresh, heated oxygen to set it ablaze. This causes the
tall and skinny appearance of a fire whirl's core.Real-world fire whirls
usually move fairly slowly. Fire whirls can set objects in their paths ablaze
and can hurl burning debris out into their surroundings. The winds generated by
a fire whirl can also be dangerous. Large fire whirls can create wind speeds of
more than 100 mph (160 km/h)—strong enough to knock down trees.Fire whirls can
last for an hour or more, and they cannot be extinguished directly.