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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 The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. History The scale was devised in 1805 by the Irish hydrographer Francis Beaufo ...
winds from every point of the compass towards the storm's center, where the air is heated and then ascends. The Black Saturday bushfires and the Great Peshtigo Fire are possible examples of forest fires with some portion of combustion due to a firestorm, as is the Great Hinckley Fire. Firestorms have also occurred in cities, usually due to targeted
explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
, such as in the aerial firebombings of London, Hamburg, Dresden, and Tokyo, and the atomic bombing of Hiroshima.


Mechanism

A firestorm is created as a result of the
stack effect The stack effect or chimney effect is the movement of air into and out of buildings through unsealed openings, chimneys, flue-gas stacks, or other containers, resulting from air buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor a ...
as the heat of the original fire draws in more and more of the surrounding air. This draft can be quickly increased if a low-level
jet stream Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...
exists over or near the fire. As the updraft mushrooms, strong inwardly-directed gusty winds develop around the fire, supplying it with additional air. This would seem to prevent the firestorm from spreading on the wind, but the tremendous turbulence created may also cause the strong surface inflow winds to change direction erratically. Firestorms resulting from the bombardment of urban areas in the Second World War were generally confined to the areas initially seeded with incendiary devices, and the firestorm did not appreciably spread outward. A firestorm may also develop into a mesocyclone and induce true tornadoes/ fire whirls. This occurred with the 2002 Durango fire, and probably with the much greater Peshtigo Fire. The greater draft of a firestorm draws in greater quantities of oxygen, which significantly increases combustion, thereby also substantially increasing the production of heat. The intense heat of a firestorm manifests largely as radiated heat ( infrared radiation), which may ignite flammable material at a distance ahead of the fire itself. This also serves to expand the area and the intensity of the firestorm. Violent, erratic wind drafts suck movables into the fire and as is observed with all intense conflagrations, radiated heat from the fire can melt asphalt, some metals, and glass, and turn street
tarmac Tarmac may refer to: Engineered surfaces * Tarmacadam, a mainly historical tar-based material for macadamising road surfaces, patented in 1902 * Asphalt concrete, a macadamising material using asphalt instead of tar which has largely superseded ta ...
into flammable hot liquid. The very high temperatures ignite anything that might possibly burn, until the firestorm runs low on fuel. A firestorm does not appreciably ignite material at a distance ahead of itself; more accurately, the heat desiccates those materials and makes them more vulnerable to ignition by embers or firebrands, increasing the rate of fire spotting. During the formation of a firestorm many fires merge to form a single convective column of hot gases rising from the burning area and strong, fire-induced, radial (inwardly directed) winds are associated with the convective column. Thus the fire front is essentially stationary and the outward spread of fire is prevented by the in-rushing wind.


Characterization of a firestorm

A firestorm is characterized by strong to gale-force winds blowing toward the fire, everywhere around the fire perimeter, an effect which is caused by the buoyancy of the rising column of hot gases over the intense mass fire, drawing in cool air from the periphery. These winds from the perimeter blow the fire brands into the burning area and tend to cool the unignited fuel outside the fire area so that ignition of material outside the periphery by radiated heat and fire embers is more difficult, thus limiting fire spread. At Hiroshima, this inrushing to feed the fire is said to have prevented the firestorm perimeter from expanding, and thus the firestorm was confined to the area of the city damaged by the blast. Large wildfire conflagrations are distinct from firestorms if they have moving fire fronts which are driven by the ambient wind and do not develop their own wind system like true firestorms. (This does not mean that a firestorm ''must'' be stationary; as with any other convective storm, the circulation may follow surrounding pressure gradients and winds, if those lead it onto fresh fuel sources.) Furthermore, non-firestorm conflagrations can develop from a single ignition, whereas firestorms have only been observed where large numbers of fires are burning simultaneously over a relatively large area, with the important caveat that the density of simultaneously burning fires needs to be above a critical threshold for a firestorm to form (a notable example of large numbers of fires burning simultaneously over a large area without a firestorm developing was the Kuwaiti oil fires of 1991, where the distance between individual fires was too large). The high temperatures within the firestorm zone ignite most everything that might possibly burn, until a tipping point is reached, that is, upon running low on fuel, which occurs after the firestorm has consumed so much of the available fuel within the firestorm zone that the necessary fuel density required to keep the firestorm's wind system active drops below the threshold level, at which time the firestorm breaks up into isolated conflagrations. In Australia, the prevalence of eucalyptus trees that have oil in their leaves results in forest fires that are noted for their extremely tall and intense flame front. Hence the bush fires appear more as a firestorm than a simple forest fire. Sometimes, emission of combustible gases from swamps (e.g.,  methane) has a similar effect. For instance, methane explosions enforced the Peshtigo Fire.


Weather and climate effects

Firestorms will produce hot buoyant smoke clouds of primarily water vapor that will form
condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
clouds as it enters the cooler upper atmosphere, generating what is known as pyrocumulus clouds ("fire clouds") or, if large enough,
pyrocumulonimbus 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 ...
("fire storm") clouds. For example, the black rain that began to fall approximately 20 minutes after the atomic bombing of Hiroshima produced in total 5–10 cm of black soot-filled rain in a 1–3 hour period. Moreover, if the conditions are right, a large pyrocumulus can grow into a pyrocumulonimbus and produce lightning, which could potentially set off further fires. Apart from city and forest fires, pyrocumulus clouds can also be produced by volcanic eruptions due to the comparable amounts of hot buoyant material formed. On a more continental and global extent, away from the direct vicinity of the fire, wildfire firestorms that produce
pyrocumulonimbus cloud 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 ...
events have been found to "surprisingly frequently" generate minor "
nuclear winter Nuclear winter is a severe and prolonged global climatic cooling effect that is hypothesized to occur after widespread firestorms following a large-scale nuclear war. The hypothesis is based on the fact that such fires can inject soot into th ...
" effects. These are analogous to minor volcanic winters, with each mass addition of
volcanic gases Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...
additive in increasing the depth of the "winter" cooling, from near-imperceptible to " year without a summer" levels.


Pyro-cumulonimbus and atmospheric effects (in wildfires)

A very important but poorly understood aspect of wildfire behavior are
pyrocumulonimbus 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 ...
(pyroCb) firestorm dynamics and their atmospheric impact. These are well illustrated in the Black Saturday case study below. The "pyroCb" is a fire-started or fire-augmented thunderstorm that in its most extreme manifestation injects huge abundances of smoke and other biomass-burning emissions into the lower stratosphere. The observed hemispheric spread of smoke and other biomass-burning emissions has known important climate consequences. Direct attribution of the stratospheric
aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...
s to pyroCbs only occurred in the last decade. Such an extreme injection by thunderstorms was previously judged to be unlikely because the extratropical tropopause is considered to be a strong barrier to convection. Two recurring themes have developed as pyroCb research unfolds. First, puzzling stratospheric aerosol-layer observations—and other layers reported as volcanic aerosol can now be explained in terms of pyroconvection. Second, pyroCb events occur surprisingly frequently, and they are likely a relevant aspect of several historic wildfires. On an intraseasonal level it is established that pyroCbs occur with surprising frequency. In 2002, at least 17 pyroCbs erupted in North America alone. Still to be determined is how often this process occurred in the boreal forests of Asia in 2002. However, it is now established that this most extreme form of pyroconvection, along with more frequent pyrocumulus convection, was widespread and persisted for at least two months. The characteristic injection height of pyroCb emissions is the upper troposphere, and a subset of these storms pollutes the lower
stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...
. Thus, a new appreciation for the role of extreme wildfire behavior and its atmospheric ramifications is now coming into focus.


Black Saturday firestorm (Wildfire case study)


Background

The Black Saturday bushfires are some of Australia's most destructive and deadly fires that fall under the category of a "firestorm" due to the extreme fire behavior and relationship with atmospheric responses that occurred during the fires. This major wildfire event led to a number of distinct electrified
pyrocumulonimbus 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 ...
plume clusters ranging roughly 15 km high. These plumes were proven susceptible to striking new spot fires ahead of the main fire front. The newly ignited fires by this pyrogenic lightning, further highlights the feedback loops of influence between the atmosphere and fire behavior on Black Saturday associated with these pyroconvective processes.


Role that pyroCbs have on fire in case study

The examinations presented here for Black Saturday demonstrate that fires ignited by lightning generated within the fire plume can occur at much larger distances ahead of the main fire front''—''of up to 100 km. In comparison to fires ignited by burning debris transported by the fire plume, these only go ahead of the fire front up to about 33 km, noting that this also has implications in relation to understanding the maximum rate of spread of a wildfire. This finding is important for the understanding and modeling of future firestorms and the large scale areas that can be affected by this phenomenon. As the individual spot fires grow together, they will begin to interact. This interaction will increase the burning rates, heat release rates, and flame height until the distance between them reaches a critical level. At the critical separation distance, the flames will begin to merge and burn with the maximum rate and flame height. As these spot fires continue to grow together, the burning and heat release rates will finally start to decrease but remain at a much elevated level compared to the independent spot fire. The flame height is not expected to change significantly. The more spot fires, the bigger the increase in burning rate and flame height.


Importance for continued study of these firestorms

Black Saturday is just one of many varieties of firestorms with these pyroconvective processes and they are still being widely studied and compared. In addition to indicating this strong coupling on Black Saturday between the atmosphere and the fire activity, the lightning observations also suggest considerable differences in pyroCb characteristics between Black Saturday and the Canberra fire event. Differences between pyroCb events, such as for the Black Saturday and Canberra cases, indicate considerable potential for improved understanding of pyroconvection based on combining different data sets as presented in the research of the Black Saturday pyroCb's (including in relation to lightning, radar, precipitation, and satellite observations). A greater understanding of pyroCb activity is important, given that fire-atmosphere feedback processes can exacerbate the conditions associated with dangerous fire behavior. Additionally, understanding the combined effects of heat, moisture, and aerosols on cloud microphysics is important for a range of weather and climate processes, including in relation to improved modeling and prediction capabilities. It is essential to fully explore events such as these to properly characterize the fire behavior, pyroCb dynamics, and resultant influence on conditions in the upper troposphere and lower stratosphere (UTLS). It is also important to accurately characterize this transport process so that cloud, chemistry, and climate models have a firm basis on which to evaluate the pyrogenic source term, pathway from the boundary layer through cumulus cloud, and exhaust from the convective column. Since the discovery of smoke in the stratosphere and the pyroCb, only a small number of individual case studies and modeling experiments have been performed. Hence, there is still much to be learned about the pyroCb and its importance. With this work scientists have attempted to reduce the unknowns by revealing several additional occasions when pyroCbs were either a significant or sole cause for the type of stratospheric pollution usually attributed to volcanic injections.


City firestorms

The same underlying combustion physics can also apply to man-made structures such as cities during war or natural disaster. Firestorms are thought to have been part of the mechanism of large urban fires, such as accompanied the
1755 Lisbon earthquake The 1755 Lisbon earthquake, also known as the Great Lisbon earthquake, impacted Portugal, the Iberian Peninsula, and Northwest Africa on the morning of Saturday, 1 November, Feast of All Saints, at around 09:40 local time. In combination with ...
, the
1906 San Francisco earthquake At 05:12 Pacific Standard Time on Wednesday, April 18, 1906, the coast of Northern California was struck by a major earthquake with an estimated moment magnitude of 7.9 and a maximum Mercalli intensity of XI (''Extreme''). High-intensity sha ...
and the
1923 Great Kantō earthquake The struck the Kantō Plain on the main Japanese island of Honshū at 11:58:44 JST (02:58:44 UTC) on Saturday, September 1, 1923. Varied accounts indicate the duration of the earthquake was between four and ten minutes. Extensive firestorms an ...
. Genuine firestorms are occurring more frequently in California wildfires, such as the 1991 wildfire disaster in Oakland, California, and the October 2017 Tubbs Fire in Santa Rosa, California. During the July–August 2018
Carr Fire The Carr Fire was a large wildfire that burned in Shasta and Trinity Counties in California, United States. The fire burned , before it was 100% contained late on August 30, 2018. The Carr Fire destroyed at least 1,604 structures (at least 1, ...
, a deadly fire vortex equivalent in size and strength to an EF-3 tornado spawned during the firestorm in Redding, California and caused tornado-like wind damage. Another wildfire which may be characterized as a firestorm was the
Camp Fire A campfire is a fire at a campsite that provides light and warmth, and heat for cooking. It can also serve as a beacon, and an insect and predator deterrent. Established campgrounds often provide a stone or steel fire ring for safety. Campfires ...
, which at one point travelled at a speed of up to 76 acres per minute, completely destroying the town of
Paradise, California Paradise is a town in Butte County, California, United States in the Sierra Nevada foothills above the northeastern Sacramento Valley. As of the 2020 census, the town population was 4,764. On November 8, 2018, a major wildfire, the Camp Fire ...
within 24 hours on November 8, 2018. Firestorms were also created by the firebombing raids of World War II in cities like Hamburg and Dresden. Of the two nuclear weapons used in combat, only Hiroshima resulted in a firestorm. In contrast, experts suggest that due to the nature of modern U.S. city design and construction, a firestorm is unlikely after a nuclear detonation.


Firebombing

Firebombing is a technique designed to damage a target, generally an urban area, through the use of fire, caused by
incendiary device Incendiary weapons, incendiary devices, incendiary munitions, or incendiary bombs are weapons designed to start fires or destroy sensitive equipment using fire (and sometimes used as anti-personnel weaponry), that use materials such as napalm, th ...
s, rather than from the blast effect of large bombs. Such raids often employ both incendiary devices and high explosives. The high explosive destroys roofs, making it easier for the incendiary devices to penetrate the structures and cause fires. The high explosives also disrupt the ability of
firefighter A firefighter is a first responder and rescuer extensively trained in firefighting, primarily to extinguish hazardous fires that threaten life, property, and the environment as well as to rescue people and in some cases or jurisdictions also ...
s to douse the fires. Although incendiary bombs have been used to destroy buildings since the start of gunpowder warfare, World War II saw the first use of strategic bombing from the air to destroy the ability of the enemy to wage war. London, Coventry, and many other British cities were firebombed during the Blitz. Most large German cities were extensively firebombed starting in 1942, and almost all large Japanese cities were firebombed during the last six months of World War II. As Sir Arthur Harris, the officer commanding
RAF Bomber Command RAF Bomber Command controlled the Royal Air Force's bomber forces from 1936 to 1968. Along with the United States Army Air Forces, it played the central role in the strategic bombing of Germany in World War II. From 1942 onward, the British bo ...
from 1942 through to the end of the war in Europe, pointed out in his post-war analysis, although many attempts were made to create deliberate man-made firestorms during World War II, few attempts succeeded: According to physicist David Hafemeister, firestorms occurred after about 5% of all fire-bombing raids during World War II (but he does not explain if this is a percentage based on both
Allied An alliance is a relationship among people, groups, or states that have joined together for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out among them. Members of an alliance are called ...
and Axis raids, or combined Allied raids, or U.S. raids alone). In 2005, the American
National Fire Protection Association The National Fire Protection Association (NFPA) is an international nonprofit organization devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards. As of 2018, the NFPA claims to have 50,000 mem ...
stated in a report that three ''major'' firestorms resulted from Allied conventional bombing campaigns during World War II: Hamburg, Dresden, and Tokyo. They do not include the comparatively minor firestorms at Kassel, Darmstadt or even Ube into their ''major'' firestorm category. Despite later quoting and corroborating Glasstone and Dolan and data collected from these smaller firestorms:


21st-century cities in comparison to World War II cities

Unlike the highly combustible World War II cities that firestormed from conventional and nuclear weapons, a FEMA report suggests that due to the nature of modern U.S. city design and construction, a firestorm is unlikely to occur even after a nuclear detonation because highrise buildings do not lend themselves to the formation of firestorms because of the baffle effect of the structures, and firestorms are unlikely in areas whose modern buildings have totally collapsed, with the exceptions of Tokyo and Hiroshima, because of the nature of their densely-packed "flimsy" wooden buildings in World War II. There is also a sizable difference between the fuel loading of World War II cities that firestormed and that of modern cities, where the quantity of combustibles per square meter in the fire area in the latter is below the necessary requirement for a firestorm to form (40 kg/m2). Therefore, firestorms are not to be expected in modern North American cities after a nuclear detonation, and are expected to be unlikely in modern European cities. Similarly, one reason for the lack of success in creating a true firestorm in the bombing of Berlin in World War II was that the building density, or builtupness factor, in Berlin was too low to support easy fire spread from building to building. Another reason was that much of the building construction was newer and better than in most of the old German city centers. Modern building practices in the Berlin of World War II led to more effective firewalls and fire-resistant construction. Mass firestorms never proved to be possible in Berlin. No matter how heavy the raid or what kinds of firebombs were dropped, no true firestorm ever developed.


Nuclear weapons in comparison to conventional weapons

The incendiary effects of a nuclear explosion do not present any especially characteristic features. In principle, the same overall result with respect to destruction of life and property can be achieved by the use of conventional incendiary and high-explosive bombs. It has been estimated, for example, that the same fire ferocity and damage produced at Hiroshima by one 16-kiloton nuclear bomb from a single
B-29 The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Fly ...
could have instead been produced by about 1,200 tons/1.2 kilotons of incendiary bombs from 220 B-29s distributed over the city; for Nagasaki, a single 21 kiloton nuclear bomb dropped on the city could have been estimated to be caused by 1,200 tons of incendiary bombs from 125 B-29s. It may seem counterintuitive that the same amount of fire damage caused by a nuclear weapon could have instead been produced by smaller total yield of thousands of incendiary bombs; however, World War II experience supports this assertion. For example, although not a perfect clone of the city of Hiroshima in 1945, in the conventional bombing of Dresden, the combined Royal Air Force (RAF) and United States Army Air Forces (USAAF) dropped a total of 3441.3 tons (approximately 3.4
kilotons TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a m ...
) of
ordnance Ordnance may refer to: Military and defense *Materiel in military logistics, including weapons, ammunition, vehicles, and maintenance tools and equipment. **The military branch responsible for supplying and developing these items, e.g., the Unite ...
(about half of which was incendiary bombs) on the night of 13–14 February 1945, and this resulted in "more than" of the city being destroyed by fire and firestorm effects according to one authoritative source, or approximately by another. In total about 4.5 kilotons of conventional ordnance was dropped on the city over a number of months during 1945 and this resulted in approximately of the city being destroyed by blast and fire effects. During the ''Operation MeetingHouse'' firebombing of Tokyo on 9–10 March 1945, 279 of the 334 B-29s dropped 1,665 tons of incendiary and high-explosive bombs on the city, resulting in the destruction of over 10,000 acres of buildings—, a quarter of the city. In contrast to these raids, when a single 16-kiloton nuclear bomb was dropped on Hiroshima, of the city was destroyed by blast, fire, and firestorm effects. Similarly, Major Cortez F. Enloe, a surgeon in the USAAF who worked with the United States Strategic Bombing Survey (USSBS), said that the 21-kiloton nuclear bomb dropped on Nagasaki did not do as much fire damage as the extended conventional airstrikes on Hamburg. File:AtomicEffects-Hiroshima.jpg, Hiroshima after the bombing and firestorm. Image:Firebombing of Tokyo.jpg, Wind blowing the smoke plume inland during the 26 May 1945 firebombing raid on Tokyo File:Hiroshima aftermath.jpg, Hiroshima aftermath. Despite a true firestorm developing, reinforced concrete buildings, as in Tokyo, similarly remained standing. Signed by the
Enola Gay The ''Enola Gay'' () is a Boeing B-29 Superfortress bomber, named after Enola Gay Tibbets, the mother of the pilot, Colonel Paul Tibbets. On 6 August 1945, piloted by Tibbets and Robert A. Lewis during the final stages of World War II, it be ...
pilot,
Paul W. Tibbets Paul Warfield Tibbets Jr. (23 February 1915 – 1 November 2007) was a brigadier general in the United States Air Force. He is best known as the aircraft captain who flew the B-29 Superfortress known as the '' Enola Gay'' (named after his mot ...
. Image:Tokyo 1945-3-10-1.jpg, This Tokyo residential section was virtually destroyed. All that remained standing were concrete buildings in this photograph.
American historian Gabriel Kolko also echoed this sentiment: This break from the linear expectation of more fire damage to occur after greater explosive yield is dropped can be easily explained by two major factors. First, the order of blast and thermal events during a nuclear explosion is not ideal for the creation of fires. In an incendiary bombing raid, incendiary weapons followed after high-explosive blast weapons were dropped, in a manner designed to create the greatest probability of fires from a limited quantity of explosive and incendiary weapons. The so-called two-ton " cookies", also known as "blockbusters", were dropped first and were intended to rupture water mains, as well as to blow off roofs, doors, and windows, creating an air flow that would feed the fires caused by the incendiaries that would then follow and be dropped, ideally, into holes created by the prior blast weapons, such into attic and roof spaces.De Bruhl (2006), pp. 210–211.Taylor, Bloomsbury 2005, pp. 287, 296, 365.Longmate (1983), pp. 162–164. On the other hand, nuclear weapons produce effects that are in the reverse order, with thermal effects and "flash" occurring first, which are then followed by the slower blast wave. It is for this reason that conventional incendiary bombing raids are considered to be a great deal more efficient at causing mass fires than nuclear weapons of comparable yield. It is likely this led the nuclear weapon effects experts
Franklin D'Olier Franklin D'Olier (April 28, 1877December 10, 1953) was an American businessman who served as the first national commander of American Legion, The American Legion from 1919 to 1920. He was also the great-grandfather of actor Christopher Reeve. ...
,
Samuel Glasstone Samuel Glasstone (3 May 1897 – 16 November 1986) was a British-born American academic and writer of scientific books. He authored over 40 popular textbooks on physical chemistry and electrochemistry, reaction rates, nuclear weapons effec ...
and
Philip J. Dolan Philip Jarvis Dolan (October 5, 1923 – January 5, 1992) was an American physicist. He graduated from West Point in 1945, was assigned to the Manhattan Project in Los Alamos in 1948, and received his MSc in physics from the University of Virginia ...
to state that the same fire damage suffered at Hiroshima could have instead been produced by about 1 kiloton/1,000 tons of incendiary bombs. The second factor explaining the non-intuitive break in the expected results of greater explosive yield producing greater city fire damage is that city fire damage is largely dependent not on the yield of the weapons used, but on the conditions in and around the city itself, with the fuel loading per square meter value of the city being one of the major factors. A few hundred strategically placed incendiary devices would be sufficient to start a firestorm in a city if the conditions for a firestorm, namely high fuel loading, are already inherent to the city (see Bat bomb). The
Great Fire of London The Great Fire of London was a major conflagration that swept through central London from Sunday 2 September to Thursday 6 September 1666, gutting the medieval City of London inside the old Roman city wall, while also extending past the ...
in 1666, although not forming a firestorm due to the single point of ignition, serves as an example that, given a densely packed and predominately wooden and thatch building construction in the urban area, a mass fire is conceivable from the mere incendiary power of no more than a domestic fireplace. On the other hand, the largest nuclear weapon conceivable will be incapable of igniting a city into a firestorm if the city's properties, namely its fuel density, are not conducive to one developing. Despite the disadvantage of nuclear weapons when compared to conventional weapons of lower or comparable yield in terms of effectiveness at starting fires, for the reasons discussed above, nuclear weapons also do not add any fuel to a city, and fires are entirely dependent on what was contained in the city prior to bombing, in direct contrast to the incendiary device effect of conventional raids. One undeniable advantage of nuclear weapons over conventional weapons when it comes to creating fires is that nuclear weapons undoubtedly produce all their thermal and explosive effects in a very short period of time. That is, to use
Arthur Harris Marshal of the Royal Air Force Sir Arthur Travers Harris, 1st Baronet, (13 April 1892 – 5 April 1984), commonly known as "Bomber" Harris by the press and often within the RAF as "Butch" Harris, was Air Officer Commanding-in-Chief (AOC-in-C) ...
's terminology, they are the epitome of an air raid guaranteed to be concentrated in "point in time". In contrast, early in World War II, the ability to achieve conventional air raids concentrated in "point of time" depended largely upon the skill of pilots to remain in formation, and their ability to hit the target whilst at times also being under heavy fire from
anti-aircraft fire Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...
from the cities below. Nuclear weapons largely remove these uncertain variables. Therefore, nuclear weapons reduce the question of whether a city will firestorm or not to a smaller number of variables, to the point of becoming entirely reliant on the intrinsic properties of the city, such as fuel loading, and predictable atmospheric conditions, such as wind speed, in and around the city, and less reliant on the unpredictable possibility of hundreds of bomber crews acting together successfully as a single unit.


See also

* Blackout (wartime) * Civilian casualties of strategic bombing *
Fire whirl 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 inte ...
* Wildfire *
Wildfire modeling In computational science, wildfire modeling is concerned with numerical simulation of wildland fires in order to understand and predict fire behavior. Wildfire modeling can ultimately aid wildland fire suppression, namely increase safety of firefi ...


Potential firestorms

Portions of the following fires are often described as firestorms, but that has not been corroborated by any reliable references: * Great Fire of Rome (64 AD) *
Great Fire of London The Great Fire of London was a major conflagration that swept through central London from Sunday 2 September to Thursday 6 September 1666, gutting the medieval City of London inside the old Roman city wall, while also extending past the ...
(1666) * Great Chicago Fire (1871) * Peshtigo Fire (1871) * San Francisco earthquake (1906) *
Great Kantō earthquake Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size * Greatness, being divine, majestic, superior, majestic, or transcendent People * List of people known as "the Great" *Artel Great (born ...
(1923) * Tillamook Burn (1933–1951) *
Second Great Fire of London The Second Great Fire of London in December 1940 was caused by one of the most destructive air raids of the Blitz during World War II. The Luftwaffe raid caused fires over an area greater than that of the Great Fire of London in 1666, leading ...
(1940) * Ash Wednesday bushfires (1983) * Yellowstone fires (1988) *
Canberra bushfires The 2003 Canberra bushfires caused severe damage to the suburbs and outer areas of Canberra, the capital city of Australia, during 18–22 January 2003. Almost 70% of the Australian Capital Territory's (ACT) pastures, pine plantations, and nat ...
(2003) *
Okanagan Mountain Park Fire On August 16, 2003, at about 4 a.m. local time, a wildfire started via lightning strike near Rattlesnake Island in Okanagan Mountain Provincial Park, British Columbia, Canada. The wildfire was fuelled by a constant wind and the driest summe ...
(2003) * Black Saturday bushfires (2009) * Fort McMurray wildfire (2016) * Predrógâo Grande wildfire (2017) *
Carr Fire The Carr Fire was a large wildfire that burned in Shasta and Trinity Counties in California, United States. The fire burned , before it was 100% contained late on August 30, 2018. The Carr Fire destroyed at least 1,604 structures (at least 1, ...
(2018)


References


Further reading

* * * * * * * * * * * * {{Natural disasters Fire