Firestorm

Firestorms have also occurred in cities, usually due to targeted explosives, such as in the aerial firebombings of London, Hamburg, Dresden, and Tokyo, and the atomic bombing of Hiroshima.

(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.)

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.

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 events have been found to "surprisingly frequently" generate minor "nuclear winter" effects.

A very important but poorly understood aspect of wildfire behavior are pyrocumulonimbus (pyroCb) firestorm dynamics and their atmospheric impact.

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.

This major wildfire event led to a number of distinct electrified pyrocumulonimbus plume clusters ranging roughly 15 km high.

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).

[20] 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).

[20] 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.

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.

[23][24] Another wildfire which may be characterized as a firestorm was the Camp Fire, which at one point travelled at a speed of up to 76 acres per minute, completely destroying the town of Paradise, California within 24 hours on November 8, 2018.

As Sir Arthur Harris, the officer commanding RAF Bomber Command 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 human-made firestorms during World War II, few attempts succeeded: "The Germans again and again missed their chance, ...of setting our cities ablaze by a concentrated attack.

[48] In 2005, the American National Fire Protection Association stated in a report that three major firestorms resulted from Allied conventional bombing campaigns during World War II: Hamburg, Dresden, and Tokyo.

[55][56][57] It may seem counterintuitive that the same amount of fire damage caused by a nuclear weapon could have instead been produced by a 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) of ordnance (about half of which was incendiary bombs) on the night of 13–14 February 1945, and this resulted in "more than" 2.5 square miles (6.5 km2) of the city being destroyed by fire and firestorm effects according to one authoritative source,[58] or approximately 8 square miles (21 km2) by another.

[60][61] In contrast to these raids, when a single 16-kiloton nuclear bomb was dropped on Hiroshima, 4.5 square miles (12 km2) of the city was destroyed by blast, fire, and firestorm effects.

[62] American historian Gabriel Kolko also echoed this sentiment: During November 1944 American B-29's began their first incendiary bomb raids on Tokyo, and on 9 March 1945, wave upon wave dropped masses of small incendiaries containing an early version of napalm on the city's population....Soon small fires spread, connected, grew into a vast firestorm that sucked the oxygen out of the lower atmosphere.

"I was a little fearful", [Secretary of War] Stimson told [President] Truman, "that before we could get ready the Air Force might have Japan so thoroughly bombed out that the new weapon would not have a fair background to show its strength."

"[63] 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.

The so-called two-ton "cookies",[35] 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 as into attic and roof spaces.

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, Samuel Glasstone and Philip J. Dolan 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.

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 from the cities below.