A fire whirl – also colloquially known as a fire devil, fire tornado, firenado, 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 or pyrocumulonimbus) cloud base. (Wikipedia)

Fire Tornado Demonstration in Singapore Science Centre

Source: guardthemind