A fire whirl, also commonly known as a fire devil, or, (in many cases erroneously) as a fire tornado, firenado, fire swirl, or fire twister, is a whirlwind induced by a fire and often (at least partially) composed of flame or ash. They usually start with a whirl of wind or smoke, and 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 vortex that sucks in burning debris and combustible gases.
Fire whirls are sometimes colloquially called fire tornadoes, but are not usually classifiable as tornadoes as the vortex in most cases does not extend from the surface to cloud base. Also, even in such cases, even those fire whirls are not classic tornadoes, in that their vorticity derives from surface winds and heat-induced lifting, rather than a tornadic mesocyclone aloft.
A fire whirl consists of a burning core and a rotating pocket of air. A fire whirl can reach up to 2,000 °F (1,090 °C). Often, fire whirls are created when a wildfire or firestorm creates its own wind, which can turn into a vortex of fire. This causes the tall and skinny appearance of a fire whirl's core.
Most of the largest fire whirls are spawned from wildfires. They form when a warm updraft and convergence from the wildfire are present. They are usually 10–50 m (33–164 ft) tall, a few meters (several feet) wide, and last only a few minutes. Some, however, can be more than 1 km (0.6 mi) tall, contain wind speeds over 200 km/h (120 mph), and persist for more than 20 minutes.
Fire whirls can uproot trees that are 15 m (49 ft) tall or more. These can also aid the 'spotting' ability of wildfires to propagate and start new fires as they lift burning materials such as tree bark. These burning embers can be blown away from the fireground by the stronger winds aloft.
An extreme example of a fire whirl is the 1923 Great Kantō earthquake in Japan, which ignited a large city-sized firestorm and produced a gigantic fire whirl that killed 38,000 people in fifteen minutes in the Hifukusho-Ato region of Tokyo.
Another example is the numerous large fire whirls (some tornadic) that developed after lightning struck an oil storage facility near San Luis Obispo, California, on 7 April 1926, several of which produced significant structural damage well away from the fire, killing two. Many whirlwinds were produced by the four-day-long firestorm coincident with conditions that produced severe thunderstorms, in which the larger fire whirls carried debris 5 km (3.1 mi) away.
During the 2003 Canberra bushfires in Canberra, Australia a violent firewhirl was documented. It was calculated to have horizontal winds of 160 mph (260 km/h) and vertical air speed of 93 mph (150 km/h), causing the flashover of 300 acres (120 ha) in 0.04 seconds. It was the first known firewhirl in Australia to have EF3 wind speeds on the Enhanced Fujita scale.
Residents in the city of Redding, California, while evacuating the area from the massive Carr Fire in late July 2018, reported seeing pyrocumulonimbus clouds and tornado-like behaviour from the firestorm, resulting in uprooted trees, cars, structures and other wind related damages in addition to the fire itself. As of August 2nd, 2018, a preliminary damage survey, led by the National Weather Service in Sacramento, California, rated the July 26th fire whirl as an EF3 tornado with winds in excess of 143 mph (230 km/h).
There are currently three known types of fire whirls:
- Type 1: Stable and centered over burning area.
- Type 2: Stable or transient, downwind of burning area.
- Type 3: Steady or transient, centered over an open area adjacent to an asymmetric burning area with wind.
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|Wikimedia Commons has media related to Fire whirls.|
- photo fire whirl outback Australia
- New, Elizabeth (1 November 2012). "Fire tornadoes: a rare weather phenomenon". Australian Geographic. Retrieved 6 March 2017.
- Fire tornado video (whirl) 11 September 2012 Alice Springs Australia
- www.abc.net.au/news Australian researchers document world-first fire tornado (Canberra). And https://www.theregister.co.uk/2012/11/21/australian_fire_tornado/
- 2013 'Fire Tornado' video. Canberra 2003 groundtrack, lee side spread, weather. 11:08
- Catalyst story: Fire Tornado
- Another photo
- www.youtube.com Video of a Fire whirl (0:30), Brazil.
- "Rare Footage of Fire Tornado". BBC. 25 August 2010.
- Video of a Fire Tornado in San Diego country
- Fire Whirl Simulations
- 1923 Great Kanto Earthquake - Fire Tornado | Video - Check123