A fire whirl, also commonly known as a fire devil or fire tornado, is a whirlwind
induced by a fire
and often (at least partially) composed of flame
or ash. These start with a whirl of wind
, often made visible by smoke
, and may occur when intense rising heat and turbulent wind conditions combine to form whirling eddies
of air. These eddies can contract a tornado
that sucks in debris and combustible gases.
The phenomenon is sometimes mislabeled a fire tornado, firenado, fire swirl, or fire twister, but these are a separate phenomenon where a fire has such intensity that it generates an actual tornado. (This phenomenon was first verified in the 2003 Canberra bushfires
and has since been verified in the 2018 Carr Fire in California and 2020 Loyalton Fire in California and Nevada.) Fire whirls 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, those fire whirls very rarely are classic tornadoes, as their vorticity
derives from surface wind
s and heat-induced lifting, rather than from a tornadic mesocyclone
A fire whirl consists of a burning core and a rotating pocket of air. A fire whirl can reach up to . Fire whirls become frequent when a wildfire
, or especially firestorm
, creates its own wind, which can spawn large vortices. Even bonfire
s often have whirls on a smaller scale and tiny fire whirls have been generated by very small fires in laboratories.
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 tall, a few meters (several feet) wide, and last only a few minutes. Some, however, can be more than tall, contain wind speed
s over , and persist for more than 20 minutes.
Fire whirls can uproot trees that are 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 fire-ground by the stronger winds aloft.
Fire whirls can be common within the vicinity of a plume
during a volcanic eruption
These range from small to large and form from a variety of mechanisms, including those akin to typical firewhirl processes, but can result in Cumulonimbus flammagenitus (cloud)
s and waterspout
or even to develop mesocyclone-like updraft rotation of the plume itself and/or of the cumulonimbi, which can spawn tornadoes similar to those in supercell
Pyrocumulonimbi generated by large fires on rare occasion also develops in a similar way.
There are currently three widely recognized 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.
There is evidence suggesting that the fire whirl in the Hifukusho-ato area, during the 1923 Great Kantō earthquake
, was of type 3.
Other mechanism and firewhirl dynamics may exist.
A broader classification of fire whirls suggested by Forman A. Williams
includes five different categories:
*Whirls generated by fuel distribution in wind
*Whirls above fuels in pools or on water
*Tilted fire whirls
*Moving fire whirls
*Whirls modified by vortex breakdown
The meteorological community views some fire-induced phenomena as atmospheric phenomena. Using the ''pyro-'' prefix, fire-induced clouds are callepyrocumulus
Larger fire vortices are similarly being viewed. Based on vortex scale, the classification terms of ''pyronado'', ''"pyrotornado"'', and ''"pyromesocyclone"'' have been proposed.
During the 1871 Peshtigo fire
, the community of Williamsonville, Wisconsin was burned by a fire whirl; the area where Williamsonville once stood is now Tornado Memorial County Park.
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
Numerous large fire whirls (some tornadic) that developed after lightning
struck an oil storage facility near San Luis Obispo
, on 7 April 1926, 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 thunderstorm
s, in which the larger fire whirls carried debris away.
Firewhirls were produced in the conflagration
s and firestorms triggered by firebombing
s of European and Japanese cities during World War II
and by the atomic bombings of Hiroshima and Nagasaki
. Firewhirls associated with the bombing of Hamburg
, particularly those of 27–28 July 1943, were studied.
Throughout the 1960s-1970s, particularly in 1978–1979, firewhirls ranging from the transient and very small to intense, long-lived tornadic-like vortices capable of causing significant damage were spawned by fires generated from the 1000 MW Météotron
, a series of large oil wells located in the Lannemezan
plain of France used for testing atmospheric motions and thermodynamics.
During the 2003 Canberra bushfires
in Canberra, Australia a violent firewhirl was documented. It was calculated to have horizontal winds of and vertical air speed of , causing the flashover
of in 0.04 seconds. It was the first known firewhirl in Australia to have EF3 wind speeds on the Enhanced Fujita scale
A fire whirl, of reportedly uncommon size for New Zealand wildfires, formed on day three of the 2017 Port Hills fires
. Pilots estimated the fire column to be high.
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 2, 2018, a preliminary damage survey, led by the National Weather Service
(NWS) in Sacramento, California
, rated the July 26th fire whirl as an EF3
tornado with winds in excess of .
On August 15, 2020, for the first time in its history, the U.S. National Weather Service issued a tornado warning for a pyrocumulonimbus
created by a wildfire near Loyalton, California
capable of producing a fire tornado.
[Matthew Cappucci (September 13, 2020) California’s wildfire smoke plumes are unlike anything previously seen]
In controlled small-scale experiments, fire whirls are found to transition to a mode of combustion called blue whirls.
The name blue whirl was coined because the soot production is negligible, leading to the disappearance of the yellow color typical of a fire whirl. Blue whirls are partially premixed flames that reside elevated in the recirculation region of the vortex-breakdown bubble. The flame length and burning rate of a blue whirl are smaller than that of a fire whirl.
* Dust devil
* Steam devil
photo fire whirl outback Australia
Fire tornado video (whirl) 11 September 2012 Alice Springs Australia
* ttp://www.abc.net.au/news/2012-11-19/researchers-document-world-first-fire-tornado/4380252 www.abc.net.au/newsAustralian 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
Video of a Fire whirl (0:30), Brazil.
Video of a Fire Tornado in San Diego country
1923 Great Kanto Earthquake - Fire Tornado | Video
Category:Severe weather and convection
Category:Types of fire
fr:Tourbillon de feu