A fire whirl - also known as a fire devil, or as a fire tornado, is a whirlwind induced by a fire when the air temperature and heat meet certain conditions. It refers to the rare phenomena that he flame forms a vertical vortex straight into the sky like a tornado. Rotating flames mostly occur in bush fires, ranging from 9 meters to 60 meters high and generally lasting only a few minutes but longer when the wind is strong.
Fire tornadoes occur when some certain conditions are met: intense heat and turbulent wind combine to form whirling eddies of air. These eddies contract into a tornado-like vortex that rotates to suck in burning debris and combustible gases. In the fire disaster, the fire tornado takes shape when the heat of the fire makes a updraft and convergence with the surrounding air swarming in all around. It is said that in Japan, when the Great Kanto Earthquake happened, fire was everywhere, several fire tornadoes occurred.
The Fire Whirl in Wisconsin
On October 8, 1871, a forest fire swept across both sides of Green Bay in northeast Wisconsin, killing perhaps 1,000 people in all. In the early October of that year, it was a typical Indian autumn, sunny and warm, with breezes and warm, dry air. In the past few weeks, there had been numerous small shrubbery and forest fires, mostly caused by the large number of branches left by loggers. Workers and nearby people were still able to keep the fire under control when the wind gently blew.
But it was Sunday, October 8, the southwesterly winds was getting stronger and stronger, developing many small fires into raging ones. At the same time, the temperature rose significantly from 19℃ on Oct. 7th to 28℃ on Oct. 8th, according to the Milwaukee station.
By the evening of October 8th, two major wildfires were slowly moving northeast around the city of Green bay. Although the residents struggled to stop them, the flames were relentless, destroying a mass of dwellings and burning all the villages from Francine to Peshtigo, from west to east.
Fire Tornado at Rancho Santa Margarita in California, USA
In May, 2002, a fire tornado caused by mountain fire at Rancho Santa margarita in California swept across the top of a ridge. It was up to 1,093℃ in the core of the fire cyclone, enough to reignite the ash sucked from the ground, according to Forthofer, the witness.
"We're not completely convinced of that," he said. "it's just a theory. It's like someone trying to set fire to something: if you expand it till it is big enough in the air, you can actually make it burn, but if it stays constrictive like a blob, it won't burn."
In 2006, a rotating column of flame curved into the air during a wildfire in Los Padres National Forest near Castaic, California.
The Fire Whirl in California
A fire tornado was approaching a residential area in the Corona fire, California, on November 15th, 2008. Where a fire tornado passed, there would be ignited objects and flaming debris being thrown around. Wind currents from tornadoes with giant flames were also rather dangerous at the speed of 160 kilometers per hour, which was strong enough to blow down trees.
The Fire Whirl in Sao Paulo A rare natural phenomenon of fire tornadoes was seen in Sao Paulo, Brazil, on August 24, 2010. This natural phenomenon was caused by a tornado turning into a huge burning dragon after passing through a burning field. There had been no rain for three months in the area before the fire tornado occurred. Unusually dry weather and strong winds fueled the fires.
Brazilian global TV television reported that the air in Sao Paulo was as dry as that in the Sahara Desert. This wind of “fire dragon” was flying about a few meters high over the burning fields, blocking one road. Helicopters were mobilized to extinguish the fire. Meanwhile, the government of Sao Paulo banned the burning of crops after harvest to prevent new fires.
The Artificial Fire Tornado in Germany
In August 2007, visitors in the Phaeno science center in Wolfsburg, Germany, watched a man-made fire tornado formed by multiple air jet vents. But fire tornadoes in reality won’t stay vertical like that, and they don't win any speed records.
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