How Fire Tornadoes Form (PHOTOS)

By: Jon Erdman

Published: August 14,2013

 

 

 

 

 

 

The inferno spun off smoke twisters, and a fire tornado formed. (Flickr/Mulling it Over)

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If you've been to the beach on a summer afternoon, you may have seen a waterspout, generally weak tornadoes forming over a body of water.
Did you know wildfires can also create their own tornadoes?
"Firewhirls" turn and bun. They are rapidly spinning vortices that form when air superheated by an intense wildfire rises rapidly, consolidating low-level spin from winds converging into the fire like a spinning ice skater, pulling its arms inward.
The typical firewhirl can grow to about 100 feet tall, but is very narrow, on the order of a couple of feet wide.
These fire vortices are likely more common than you think. Given the proliferation of cameras, smartphones and social media, we're seeing more documentation of this phenomenon recently.
A firewhirl formed in a wildfire in Summit County, Utah this week.  In September 2012, cameraman Chris Tangey filmed this incredible firewhirl in Australia. Another was captured on video in Brazil in 2010.
You may have seen what appears to be a growing thunderhead above an intense wildfire. Like any other cloud, this so-called pyrocumulus cloud is produced when rising air eventually condenses its water vapor into cloud droplets. It just so happens the hot, rising air is provided by a wildfire.
If the growing pyrocumulus cloud provides a strong enough updraft, an existing firewhirl can grow much larger, resembling a conventional tornado.
A study released in late 2012 documented the process of "pyro-tornadogenesis" for the first time in the January 2003 Canberra, Australia wildfires.
This fire tornado, roughly one-third of a mile wide, produced at least EF2 damage on the Enhanced-Fujita scale, including blowing off roofs of homes.