1. Formation

2. Classification

3. Notable examples

4. See also

5. References

6. Further reading

7. External links

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. 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-like vortex that sucks in 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, those fire whirls very rarely are classic tornadoes, as their vorticity derives from surface winds and heat-induced lifting, rather than from a tornadic mesocyclone aloft, although a handful of suspected cases of the latter are known.^[1]

Formation

A fire whirl consists of a burning core and a rotating pocket of air. A fire whirl can reach up to {{convert|2,000|F|C}}.^[2] Fire whirls become frequent when a wildfire, or especially firestorm, creates its own wind, which can spawn large vortices. Even bonfires often have whirls on a smaller scale and tiny firewhirls have been generated by very small fires in laboratories.^[3]

Most of the largest fire whirls are spawned from wildfires. They form when a warm updraft and convergence from the wildfire are present.^[4] They are usually {{convert|10|–|50|m|abbr=on}} tall, a few meters (several feet) wide, and last only a few minutes. Some, however, can be more than {{convert|1|km|mi|sigfig=1|abbr=on}} tall, contain wind speeds over {{convert|200|km/h|mph|abbr=on}}, and persist for more than 20 minutes.^[5]

Fire whirls can uproot trees that are {{convert|15|m|ft|abbr=on}} tall or more.^[6] 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.

Firewhirls can be common within the vicinity of a plume during a volcanic eruption.^[7][8] 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) spawning landspouts and waterspouts^[9] or even to develop mesoyclone-like updraft rotation of the plume itself and/or of the cumulonimbi, which can spawn tornadoes similar to those in supercells.^[10] Pyrocumulonimbi generated by large fires on rare occasion also develops in a similar way.^{[11][1][12][13]}

Classification

There are currently three widely recognized types of fire whirls:^[14]

• 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.^[15] Other mechanism and firewhirl dynamics may exist.^[16]

Notable examples

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.^[17]

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 {{convert|5|km|abbr=on}} away.^[18]

Firewhirls were produced in the conflagrations and firestorms triggered by firebombings of European and Japanese cities during World War Two 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.^[19]

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.^[20]

During the 2003 Canberra bushfires in Canberra, Australia a violent firewhirl was documented. It was calculated to have horizontal winds of {{convert|160|mph|abbr=on}} and vertical air speed of {{convert|93|mph|abbr=on}}, causing the flashover of {{convert|300|acres}} in 0.04 seconds.^[21] It was the first known firewhirl in Australia to have EF3 wind speeds on the Enhanced Fujita scale.^[22]

A fire whirl, of reportedly uncommon size for New Zealand wildfires, formed on day three of the 2017 Port Hills fires in Christchurch. Pilots estimated the fire column to be {{convert|100|m|abbr=on}} high.^[23]

Residents in the city of Redding, California, while evacuating the area from the massive Carr Fire in late July 2018, reported seeing pyrocumulonimbusclouds 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 {{convert|143|mph|abbr=on}}.^[24]

See also

• Dust devil
• Steam devil

References

Further reading

• {{cite journal |last = Graham |first = Howard E. |title = Fire Whirlwinds |journal = Bull. Am. Meteorol. Soc. |volume = 36 |issue = 3 |pages = 99–103 |date = 1955 |doi = 10.1175/1520-0477-36.3.99 }}

External links

• [https://www.flickr.com/photos/christangey/15034579939 photo fire whirl outback Australia]
• {{cite web | url=http://www.australiangeographic.com.au/topics/science-environment/2012/11/fire-tornadoes-a-rare-weather-phenomenon/ | title=Fire tornadoes: a rare weather phenomenon | first=Elizabeth | last=New | date=1 November 2012 | work=Australian Geographic | accessdate=6 March 2017 }}
• Fire tornado video (whirl) 11 September 2012 Alice Springs Australia
• Photo
• 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/
• [https://www.youtube.com/watch?v=rqYEeivt8Eg 2013 'Fire Tornado' video. Canberra 2003 groundtrack, lee side spread, weather. 11:08 ]
• Catalyst story: Fire Tornado
• Another photo
• [https://www.youtube.com/watch?v=ssn2kmNf0ME www.youtube.com] Video of a Fire whirl (0:30), Brazil.
• {{cite web |url=https://www.bbc.co.uk/news/world-latin-america-11086299 |title=Rare Footage of Fire Tornado |authorlink= |date=25 August 2010 |work= |publisher=BBC |location= |page= |pages= |at= |language= |trans-title=|format= |doi= |accessdate= |quote= |ref= }}
• Video of a Fire Tornado in San Diego country
• Fire Whirl Simulations
• [https://www.check123.com/videos/9520-1923-great-kanto-earthquake-fire-tornado 1923 Great Kanto Earthquake - Fire Tornado | Video] - Check123

• Iijima Kōichi
• IIJ (Malta)
• IIJmio
• Iika Heino
• I.I. Karzinkin House
• II (Khun Narin album)
• Iikka Heino
• II Kultepe
• I Il
• Iilahti, Jonathan
• II. Lajos
• II (Last in Line album)
• II liga (Poland)
• Iilish Ross
• IILM University
• II (Lords of Black album)
• II Lupi
• IIM Act
• IIM Act, 2017
• II (Majical Cloudz album)
• II Marine Amphibious Force
• IIM BG
• IIM Bill
• IIM Bill, 2017
• IIM Bodh Gaya