A vigorously rotating column of flame or ash generated when intense heat from a wildfire, combined with turbulent winds, causes rising hot air to spin, in effect a fire-driven tornado. The most extreme examples, sometimes called firenadoes, can uproot trees, hurl burning debris and generate their own lightning. The 1923 Great Kanto earthquake fire in Tokyo produced a fire whirl that killed tens of thousands of people sheltering in an open field.
Facts
PeriodicityNot tied to a season; fire whirls become frequent whenever a wildfire or, especially, a firestorm generates enough of its own wind to spawn large vortices, from small whirls on ordinary bonfires to city-scale events during major firestorms. 1 ScaleMost are 10 to 50 meters (33 to 164 feet) tall, only a few meters wide, and last just a few minutes; the largest exceed 1 kilometer (five-eighths of a mile) in height, carry winds over 200 km/h (120 mph), and can persist more than 20 minutes. 1 First DescribedAn early scientific treatment appears in Howard E. Graham's 1955 paper Fire Whirlwinds, published in the Bulletin of the American Meteorological Society. 1 Identification
Distinguishing AppearanceA burning core wrapped in a rotating pocket of air, forming a tornado-like vortex of flame and ash that can reach temperatures up to 1,100 degrees Celsius (2,000 degrees Fahrenheit). 1 Connections
Demonstrated By
Source National Oceanic and Atmospheric Administration
Sources
1. Fire Whirl (Wikipedia)
WikipediaFormation section (frequency sentence)
Fire whirls become frequent when a wildfire, or especially firestorm, creates its own wind, which can spawn large vortices.
Formation section (size sentence)
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 (5⁄8 mi) tall, contain wind speeds over 200 km/h (120 mph), and persist for more than 20 minutes.
Formation section (structure sentence)
A fire whirl consists of a burning core and a rotating pocket of air. A fire whirl can reach up to 1,100 °C (2,000 °F).
Further reading section
Graham, Howard E. (1955). "Fire Whirlwinds". Bull. Am. Meteorol. Soc. 36 (3): 99-103.
View the Source National Oceanic and Atmospheric Administration
National Oceanic and Atmospheric AdministrationDemonstrated By: ChaparralView the Source Reader Challenges (0)
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