A ‘firenado’ or fire whirl is a whirlwind induced by a fire. 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. Combustible, carbon-rich gases released by burning vegetation on the ground are fuel for most fire whirls.
Real-world fire whirls usually move fairly slowly. They 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- strong enough to knock down trees. They can also last for an up to an hour or more, and they cannot be extinguished directly.
Check out this video of a “firenado” in Australia shot by Chris Tangey in 2012