Science Fair Project Encyclopedia
A firestorm is the mass movement of air resulting from fire, creating a fire of extreme intensity over a wide area. It is most commonly a natural phenomenon, created during forest fires, and some of the largest forest fires, such as the Great Peshtigo Fire, have been firestorms. A firestorm can also be a deliberate effect of targeted explosives.
Mechanism of firestorms
After an area catches fire, the air above the area becomes extremely hot and rises rapidly. Cold air then rushes in at ground level from the outside to replace the rising air, creating high winds which fan the flames at ground level further. This creates a self-sustaining 'firestorm' with temperatures peaking at over 2,000 degrees Celsius fed by the influx of oxygen.
Experiments with test fires have shown that firestorms can create fast-moving vortices of fire, which can spread the fire beyond the area of the original fire. The winds in some of these fire vortices can reach tornadic strengths, effectively creating a "fire tornado." These fiery tornadoes can complicate the jobs of firefighters in combating the inferno.
An extremely large firestorm can even create its own weather system, drawing air inward and creating thunderstorm-like weather which tends to aid the spread of the flames.
Firestorms in cities
The same underlying combustion physics can also apply to man-made structures such as cities.
Firestorms are thought to have been part of the mechanism of large urban fires such as the Great Chicago Fire, Great Fire of Rome, the Great Fire of London, and the fire resulting from the 1906 San Francisco earthquake.
Firestorms were also created by the firebombing raids of World War II in Hamburg (see: Operation Gomorrah), Dresden (see: bombing of Dresden in World War II), Tokyo (see: bombing of Tokyo in World War II), Kassel (see: bombing of Kassel in World War II), Darmstadt, and Stuttgart.
The fire-bombing consisted of dropping large amounts of high explosives to expose the timbers within buildings, followed by incendiary devices (fire-sticks) to ignite them and then more high explosives to hamper the efforts of the fire services. It is said that in the Dresden firebombing, people melted and caught fire in the resulting furnace conditions.
- crown fire
- John Fleck, "Firestorms Get New Spin", The Albuquerque Journal, May 14, 2000.
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