Fire whirl
A fire whirl, colloquially fire devil, fire tornado, or fire storm, is a rare phenomenon in which a fire, under certain conditions (depending on air temperature and currents), acquires a vertical vorticity and forms a whirl, or a tornado-like vertically oriented rotating column of air. Fire whirls may be whirlwinds separated from the flames, either within the burn area or outside it, or a vortex of flame, itself.
An extreme example 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 in fifteen minutes in the Hifukusho-Ato region of Tokyo.[1] 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 April 7, 1926, several of which produced significant structural damage well away from the fire, killing two. Thousands of 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 kilometers (3 mi) away.[2]
Most of the largest fire tornados are spawned from wildfires. They form when a warm updraft and convergence from the wildfire are present.[3] They are usually 10-50 meters (30-200 ft) tall, a few meters (~10 ft) wide, and last only a few minutes. However, some can be more than a kilometer (0.6 mile) tall, contain winds over 160 km/h (100 mph), and persist for more than 20 minutes.[4]
Fire whirls can uproot trees up to 15 metres (49 ft) tall.[5]
These can also aid the 'spotting' ability of wildfires to propagate and start new fires.
See also
References
- ^ Quintiere, James G. (1998). Principles of Fire Behavior. Thomson Delmar Learning. ISBN 0827377320.
- ^ Hissong, J. E. (1926). "Whirlwinds At Oil-Tank Fire, San Luis Obispo, Calif" (abstract). Monthly Weather Review. 54 (4): 161–3. doi:10.1175/1520-0493(1926)54<161:WAOFSL>2.0.CO;2.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Umscheid, Michael E. (2006). "Photographs and Analysis of an Unusually Large and Long-lived Firewhirl". Electronic Journal of Severe Storms Meteorology. 1 (2).
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Grazulis, Thomas P. (1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, VT: The Tornado Project of Environmental Films. ISBN 1879362031.
{{cite book}}: Unknown parameter|month=ignored (help) - ^ Otways Fire No. 22 - 1982/83 Aspects of fire behaviour. Research Report No.20 (PDF). Victoria Department of Sustainability and Environment. June 1983. Retrieved 2009-06-26.
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- Church, Christopher R. (1980). "Intense Atmospheric Vortices Associated with a 1000 MW Fire" (abstract). Bulletin of the American Meteorological Society. 61 (7): 682–694. doi:10.1175/1520-0477(1980)061<0682:IAVAWA>2.0.CO;2.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - Fire Whirl Simulations
