When you picture a tornado, most of us imagine a whirling column of air poking down from the clouds. But this tornado-like effect is not limited to just the air – a fire tornado or fire whirl is just like a tornado but it’s made of fire. As the heated air from the fire rises, strong air currents (often whipping through the trees) cause the air molecules to spin (often referred to as angular or rotational momentum) which shapes the flame into the shape of a tornado. This catches the tops of trees on fire and the fire jumps from tree top to tree top.
The phenomenon has been recently seen in large wildfires in Russia and closer to home in the Fourmile Canyon Fire outside of Boulder, Colorado.
For more on Fire Tornadoes, read the experiment.