Fire whirl

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Fire whirl
Fire whirl (FWS) crop.jpg
A fire whirl with flames in the vortex
Area of occurrenceWorldwide (most frequent in areas subject to wildfires)
SeasonAll year (most frequent in dry season)
EffectWind damage, burning, propagation/intensification of fires

A fire whirl or fire devil (sometimes referred to as a 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-like vortex that sucks in debris and combustible gases.

Contents

The phenomenon is sometimes labeled a fire tornado, firenado, fire swirl, or fire twister, but these terms usually refer to a separate phenomenon where a fire has such intensity that it generates an actual tornado. 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 winds and heat-induced lifting, rather than from a tornadic mesocyclone aloft. [1]

The 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.

Formation

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). [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 fire whirls 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 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. [5]

Fire whirls can uproot trees that are 15 m (49 ft) 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 fire-ground by the stronger winds aloft.

Fire whirls 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 fire whirl processes, but can result in Cumulonimbus flammagenitus (cloud) spawning landspouts and waterspouts [9] 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 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]

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 fire whirl dynamics may exist. [16] A broader classification of fire whirls suggested by Forman A. Williams includes five different categories: [17]

The meteorological community views some fire-induced phenomena as atmospheric phenomena. Using the pyro- prefix, fire-induced clouds are called pyrocumulus and pyrocumulonimbus. Larger fire vortices are similarly being viewed. Based on vortex scale, the classification terms of pyronado, "pyrotornado", and "pyromesocyclone" have been proposed. [18]

Notable examples

A flame-filled fire whirl Fire-whirl.jpg
A flame-filled fire whirl

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. [19] [20] [21]

An extreme example of a fire whirl is the 1923 Great Kantō earthquake in Japan, which ignited a large city-sized firestorm which in turn produced a gigantic fire whirl that killed 38,000 people in fifteen minutes in the Hifukusho-Ato region of Tokyo. [22]

Numerous large fire whirls (some tornadic) that developed after lightning struck an oil storage facility near San Luis Obispo, California, 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 thunderstorms, in which the larger fire whirls carried debris 5 km (3.1 mi) away. [23]

Fire whirls were produced in the conflagrations and firestorms triggered by firebombings of European and Japanese cities during World War II and by the atomic bombings of Hiroshima and Nagasaki. Fire whirls associated with the bombing of Hamburg, particularly those of 27–28 July 1943, were studied. [24]

Throughout the 1960s and 1970s, particularly in 1978–1979, fire whirls ranging from the transient and very small to intense, long-lived tornado-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. [25]

During the 2003 Canberra bushfires in Canberra, Australia, a violent fire whirl 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. [26] It was the first known fire whirl in Australia to have EF3 wind speeds on the Enhanced Fujita scale. [27]

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 100 m (330 ft) high. [28]

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 143 mph (230 km/h). [29]

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. [30] [31] [32]

Blue whirl

In controlled small-scale experiments, fire whirls are found to transition to a mode of combustion called blue whirls. [33] 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. [34] The flame length and burning rate of a blue whirl are smaller than those of a fire whirl. [33]

See also

Related Research Articles

<span class="mw-page-title-main">Tornado</span> Violently rotating column of air in contact with both the Earths surface and a cumulonimbus cloud

A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), are more than 3 kilometers (2 mi) in diameter, and stay on the ground for more than 100 km (62 mi).

<span class="mw-page-title-main">Cyclone</span> Large scale air mass that rotates around a strong center of low pressure

In meteorology, a cyclone is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above. Cyclones are characterized by inward-spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes, and dust devils lie within the smaller mesoscale.

<span class="mw-page-title-main">Dust devil</span> Type of whirlwind

A dust devil is a strong, well-formed, and relatively short-lived whirlwind. Its size ranges from small to large. The primary vertical motion is upward. Dust devils are usually harmless, but can on rare occasions grow large enough to pose a threat to both people and property.

<span class="mw-page-title-main">Supercell</span> Thunderstorm that is characterized by the presence of a mesocyclone

A supercell is a thunderstorm characterized by the presence of a mesocyclone; a deep, persistently rotating updraft. Due to this, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms, supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres (20 mi) away. They tend to last 2–4 hours.

<span class="mw-page-title-main">Peshtigo fire</span> 1871 forest fire that destroyed Peshtigo, Wisconsin, US

The Peshtigo fire was a large forest fire on October 8, 1871, in northeastern Wisconsin, United States, including much of the southern half of the Door Peninsula and adjacent parts of the Upper Peninsula of Michigan. The largest community in the affected area was Peshtigo, Wisconsin, which had a population of approximately 1,700 residents. The fire burned about 1.2 million acres and is the deadliest wildfire in recorded history, with the number of deaths estimated between 1,500 and 2,500. Although the exact number of deaths is debated, mass graves, both those already exhumed and those still being discovered, in Peshtigo and the surrounding areas show that the death toll of the blaze was most likely greater than the 1889 Johnstown flood death toll of 2,200 people or more.

<span class="mw-page-title-main">Firestorm</span> High intensity conflagration

A firestorm is a conflagration which attains such intensity that it creates and sustains its own wind system. It is most commonly a natural phenomenon, created during some of the largest bushfires and wildfires. Although the term has been used to describe certain large fires, the phenomenon's determining characteristic is a fire with its own storm-force winds from every point of the compass towards the storm's center, where the air is heated and then ascends.

<span class="mw-page-title-main">Hook echo</span> Weather radar signature indicating tornadic circulation in a supercell thunderstorm

A hook echo is a pendant or hook-shaped weather radar signature as part of some supercell thunderstorms. It is found in the lower portions of a storm as air and precipitation flow into a mesocyclone, resulting in a curved feature of reflectivity. The echo is produced by rain, hail, or even debris being wrapped around the supercell. It is one of the classic hallmarks of tornado-producing supercells. The National Weather Service may consider the presence of a hook echo coinciding with a tornado vortex signature as sufficient to justify issuing a tornado warning.

<span class="mw-page-title-main">Anticyclonic storm</span> Type of storm

An anticyclonic storm is a storm with a high-pressure center, in which winds flow in the direction opposite to that of the flow above a region of low pressure. These storms can create powerful mesoanticylonic supercell storms that can generate anticyclonic tornadoes. Examples include the anticyclonic blizzard of 2018, Hartmut, Jupiter, and Neptune's anticyclonic cloud system.

<span class="mw-page-title-main">Funnel cloud</span> Funnel-shaped cloud extending from a cloud base but doesnt touch the ground

A funnel cloud is a funnel-shaped cloud of condensed water droplets, associated with a rotating column of wind and extending from the base of a cloud but not reaching the ground or a water surface. A funnel cloud is usually visible as a cone-shaped or needle like protuberance from the main cloud base. Funnel clouds form most frequently in association with supercell thunderstorms, and are often, but not always, a visual precursor to tornadoes. Funnel clouds are visual phenomena, these are not the vortex of wind itself.

<span class="mw-page-title-main">Multiple-vortex tornado</span> Tornado comprising multiple vortices

A multiple-vortex tornado is a tornado that contains several vortices revolving around, inside of, and as part of the main vortex. The only times multiple vortices may be visible are when the tornado is first forming or when condensation and debris are balanced such that subvortices are apparent without being obscured. They can add over 100 mph to the ground-relative wind in a tornado circulation and are responsible for most cases where narrow arcs of extreme destruction lie right next to weak damage within tornado paths.

<span class="mw-page-title-main">Landspout</span> Tornado not originating from a mesocyclone

Landspout is a term created by atmospheric scientist Howard B. Bluestein in 1985 for a tornado not associated with a mesocyclone. The Glossary of Meteorology defines a landspout as

<span class="mw-page-title-main">Eye (cyclone)</span> Central area of calm weather in a tropical cyclone

The eye is a region of mostly calm weather at the center of a tropical cyclone. The eye of a storm is a roughly circular area, typically 30–65 kilometers in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather and highest winds of the cyclone occur. The cyclone's lowest barometric pressure occurs in the eye and can be as much as 15 percent lower than the pressure outside the storm.

<span class="mw-page-title-main">Cumulonimbus flammagenitus</span> Thunderstorm cloud that forms above a heat source

The cumulonimbus flammagenitus cloud (CbFg), also known as the pyrocumulonimbus cloud, is a type of cumulonimbus cloud that forms above a source of heat, such as a wildfire or volcanic eruption, and may sometimes even extinguish the fire that formed it. It is the most extreme manifestation of a flammagenitus cloud. According to the American Meteorological Society’s Glossary of Meteorology, a flammagenitus is "a cumulus cloud formed by a rising thermal from a fire, or enhanced by buoyant plume emissions from an industrial combustion process."

<span class="mw-page-title-main">Tornadogenesis</span> Process by which a tornado forms

Tornadogenesis is the process by which a tornado forms. There are many types of tornadoes and these vary in methods of formation. Despite ongoing scientific study and high-profile research projects such as VORTEX, tornadogenesis is a volatile process and the intricacies of many of the mechanisms of tornado formation are still poorly understood.

<span class="mw-page-title-main">Tornado family</span> Succession of tornadoes originating from the same storm cell

A tornado family is a series of tornadoes spawned by the same supercell thunderstorm. These families form a line of successive or parallel tornado paths and can cover a short span or a vast distance. Tornado families are sometimes mistaken as a single continuous tornado, especially prior to the 1970s. Sometimes the tornado tracks can overlap and expert analysis is necessary to determine whether or not damage was created by a family or a single tornado. In some cases, such as the Hesston-Goessel, Kansas tornadoes of March 1990, different tornadoes of a tornado family merge, making discerning whether an event was continuous or not more difficult.

<span class="mw-page-title-main">Tornado vortex signature</span>

A tornadic vortex signature, abbreviated TVS, is a Pulse-Doppler radar weather radar detected rotation algorithm that indicates the likely presence of a strong mesocyclone that is in some stage of tornadogenesis. It may give meteorologists the ability to pinpoint and track the location of tornadic rotation within a larger storm, and is one component of the National Weather Service's warning operations.

<span class="mw-page-title-main">Dry thunderstorm</span> Thunderstorm where little to no precipitation reaches the ground

A dry thunderstorm is a thunderstorm that produces thunder and lightning, but where most of its precipitation evaporates before reaching the ground. Dry lightning refers to lightning strikes occurring in this situation. Both are so common in the American West that they are sometimes used interchangeably.

A mesovortex is a small-scale rotational feature found in a convective storm, such as a quasi-linear convective system, a supercell, or the eyewall of a tropical cyclone. Mesovortices range in diameter from tens of miles to a mile or less and can be immensely intense.

The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.

References

  1. 1 2 McRae, Richard H. D.; J. J. Sharples; S. R. Wilkes; A. Walker (2013). "An Australian pyro-tornadogenesis event". Nat. Hazards. 65 (3): 1801–1811. Bibcode:2013NatHa..65.1801M. doi:10.1007/s11069-012-0443-7. S2CID   51933150.
  2. ↑ Fortofer, Jason (20 September 2012) "New Fire Tornado Spotted in Australia" Archived 27 July 2019 at the Wayback Machine National Geographic
  3. ↑ Chuah, Keng Hoo; K. Kuwana (2009). "Modeling a fire whirl generated over a 5-cm-diameter methanol pool fire". Combust. Flame. 156 (9): 1828–1833. doi:10.1016/j.combustflame.2009.06.010.
  4. ↑ Umscheid, Michael E.; Monteverdi, J.P.; Davies, J.M. (2006). "Photographs and Analysis of an Unusually Large and Long-lived Firewhirl". Electronic Journal of Severe Storms Meteorology . 1 (2): 1–13. doi: 10.55599/ejssm.v1i2.3 .
  5. ↑ Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, VT: The Tornado Project of Environmental Films. ISBN   1-879362-03-1.
  6. ↑ Billing, P., ed. (June 1983). Otways Fire No. 22 – 1982/83 Aspects of fire behaviour. Research Report No.20 (PDF). Victoria Department of Sustainability and Environment. Archived from the original on 3 May 2013. Retrieved 19 December 2012.
  7. ↑ Thorarinsson, Sigurdur; B. Vonnegut (1964). "Whirlwinds Produced by the Eruption of Surtsey Volcano". Bull. Am. Meteorol. Soc. 45 (8): 440–444. Bibcode:1964BAMS...45..440T. doi: 10.1175/1520-0477-45.8.440 .
  8. ↑ Antonescu, Bogdan; D. M. Schultz; F. Lomas (2016). "Tornadoes in Europe: Synthesis of the Observational Datasets". Mon. Wea. Rev. 144 (7): 2445–2480. Bibcode:2016MWRv..144.2445A. doi: 10.1175/MWR-D-15-0298.1 .
  9. ↑ Lareau, N. P.; N. J. Nauslar; J. T. Abatzoglou (2018). "The Carr Fire Vortex: A Case of Pyrotornadogenesis?". Geophys. Res. Lett. 45 (23): 13107–13115. Bibcode:2018GeoRL..4513107L. doi: 10.1029/2018GL080667 .
  10. ↑ Chakraborty, Pinaki; G. Gioia; S. W. Kieffer (2009). "Volcanic mesocyclones". Nature. 458 (7237): 497–500. Bibcode:2009Natur.458..497C. doi:10.1038/nature07866. PMID   19325632. S2CID   1129142.
  11. ↑ Cunningham, Phillip; M. J. Reeder (2009). "Severe convective storms initiated by intense wildfires: Numerical simulations of pyro-convection and pyro-tornadogenesis". Geophys. Res. Lett. 36 (12): L12812. Bibcode:2009GeoRL..3612812C. doi:10.1029/2009GL039262. S2CID   128775258.
  12. ↑ Fromm, Michael; A. Tupper; D. Rosenfeld; R. Servranckx; R. McRae (2006). "Violent pyro-convective storm devastates Australia's capital and pollutes the stratosphere". Geophys. Res. Lett. 33 (5): L05815. Bibcode:2006GeoRL..33.5815F. doi: 10.1029/2005GL025161 . S2CID   128709657.
  13. ↑ Kinniburgh, David C.; M. J. Reeder; T. P. Lane (2016). "The dynamics of pyro-tornadogenesis using a coupled fire-atmosphere model". 11th Symposium on Fire and Forest Meteorology. Minneapolis, MN: American Meteorological Society.
  14. ↑ Williams, Forman (22 May 2009). "The Occurrence and Mechanisms of Fire Whirls" (PDF). La Lolla, California; Valladolid, Spain: MAE UCSD; Spanish Section of the Combustion Institute. Archived from the original (PDF) on 13 May 2014.
  15. ↑ Kuwana, Kazunori; Sekimoto, Kozo; Saito, Kozo; Williams, Forman A. (May 2008). "Scaling fire whirls". Fire Safety Journal. 43 (4): 252–7. doi:10.1016/j.firesaf.2007.10.006.
  16. ↑ Chuah, Keng Hoo; K. Kuwana; K. Saito; F. A. Williams (2011). "Inclined fire whirls". Proc. Combust. Inst. 33 (2): 2417–2424. doi:10.1016/j.proci.2010.05.102.
  17. ↑ Williams, Forman A. (2020). "Scaling considerations for fire whirls". Progress in Scale Modeling. 1 (1): 1–4. doi:10.13023/psmij.2020.02.
  18. ↑ McCarthy, Patrick; Cormier, Leanne (23 September 2020). "Proposed Nomenclature for Fire-induced Vortices". CMOS BULLETIN SCMO. Canadian Meteorological and Oceanographic Society. Archived from the original on 20 October 2020. Retrieved 18 October 2020.
  19. ↑ Tornadoes of Fire at Williamsonville, Wisconsin, October 8, 1871 Archived 9 October 2022 at Ghost Archive by Joseph M. Moran and E. Lee Somerville, 1990, Wisconsin Academy of Sciences, Arts, and Letters, 31 pp.
  20. ↑ Skiba, Justin (2 September 2016). "The Fire That Took Williamsonville". Door County Living. Archived from the original on 24 September 2020. Retrieved 22 January 2019.
  21. ↑ Tornado Memorial Park kiosk historical notes, also see p. 19 Archived 24 June 2021 at the Wayback Machine of the County C Park and Ride lot panel draft pdf
  22. ↑ Quintiere, James G. (1998). Principles of Fire Behavior. Thomson Delmar Learning. ISBN   0-8273-7732-0.
  23. ↑ Hissong, J. E. (1926). "Whirlwinds At Oil-Tank Fire, San Luis Obispo, Calif". Mon. Wea. Rev. 54 (4): 161–3. Bibcode:1926MWRv...54..161H. doi: 10.1175/1520-0493(1926)54<161:WAOFSL>2.0.CO;2 .
  24. ↑ Ebert, Charles H. V. (1963). "The Meteorological Factor in the Hamburg Fire Storm". Weatherwise. 16 (2): 70–75. Bibcode:1963Weawi..16b..70E. doi:10.1080/00431672.1963.9941009.
  25. ↑ Church, Christopher R.; Snow, John T.; Dessens, Jean (1980). "Intense Atmospheric Vortices Associated with a 1000 MW Fire". Bull. Am. Meteorol. Soc. 61 (7): 682–694. Bibcode:1980BAMS...61..682C. doi: 10.1175/1520-0477(1980)061<0682:IAVAWA>2.0.CO;2 .
  26. ↑ "Fire tornado video". ACT Emergency Services. Archived from the original on 28 November 2018. Retrieved 28 November 2018.
  27. ↑ "California 'fire tornado' had 143 mph (230 km/h) winds, possibly state's strongest twister ever". USA Today. 3 August 2018. Archived from the original on 28 November 2018. Retrieved 28 November 2018.
  28. ↑ van Beynen, Martin (11 March 2017). "Firestorm". The Press . pp. C1–C4. Archived from the original on 12 March 2017. Retrieved 12 March 2017.
  29. ↑ Erdman, Jonathan (3 August 2018). "The Giant Fire Whirl From California's Carr Fire Produced Damage Similar to an EF3 Tornado in Redding, an NWS Survey Found". The Weather Channel. Archived from the original on 5 August 2018. Retrieved 16 February 2019.
  30. ↑ "A 'fire tornado' warning? Weather service issues what could be a first at California blaze". Archived from the original on 16 August 2020. Retrieved 16 August 2020.
  31. ↑ Herzmann, Daryl. "IEM :: Valid Time Event Code (VTEC) App". mesonet.agron.iastate.edu. Archived from the original on 1 September 2020. Retrieved 14 September 2020.
  32. ↑ "Matthew Cappucci (September 13, 2020) California's wildfire smoke plumes are unlike anything previously seen". MSN . Archived from the original on 14 September 2020. Retrieved 14 September 2020.
  33. 1 2 Xiao, Huahua; Gollner, Michael J.; Oran, Elaine S. (2016). "From fire whirls to blue whirls and combustion with reduced pollution". Proceedings of the National Academy of Sciences. 113 (34): 9457–9462. arXiv: 1605.01315 . Bibcode:2016PNAS..113.9457X. doi: 10.1073/pnas.1605860113 . PMC   5003231 . PMID   27493219.
  34. ↑ Coenen, Wilfried; Kolb, Erik J.; Sánchez, Antonio L.; Williams, Forman A. (July 2019). "Observed dependence of characteristics of liquid-pool fires on swirl magnitude". Combustion and Flame. 205: 1–6. arXiv: 2202.06567 . doi:10.1016/j.combustflame.2019.03.032. S2CID   132260032.

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