By: T.M. Giannaros
One of the most impressive and often dangerous manifestations of extreme fire behaviour are fire whirls. Such a fire whirl was observed on Wednesday 18 August 2021 during the Vilia wildfire in western Attica, Greece. As shown in the following video that Danielia Makka captured with her phone, the fire whirl was strong enough to uproot a tree, which seconds after landed very close to firefighters and volunteers operating in the area.
In meteorological terms, a fire whirl is a vortex generated by the intense heating of a fire. It is typically composed of ashes and flames, and temperature at each core can reach up to 1,090 degrees Celcius. A burning core and a rotating pocket of air are the two primary components of fire whirls, which can reach up to 50 m in height, be several meters wide, and last from less than a minute up to 20 minutes or more. For a fire whirl to occur, intense heating is the key ingredient. As large amounts of heat and vapour are released by the burning of rich and dry fuels, the fire begins producing strong updrafts. Air from around the burning zone begins rushing in to replace the upward moving warm air, converges, and begins rotating. Eventually, a fire whirl is born. Fire whirls are of paramount importance as they can jeopardise the safety of firefighters. Strong fire whirls are able to uproot trees up to 15 m, while they can effectively increase the density of fire spotting and thus contribute to the erratic spread of the fire.
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