![]() ![]() The heads of the clouds themselves consist of highly radioactive particles, primarily the fission products and other weapon debris aerosols, and are usually dispersed by the wind, though weather patterns (especially rain) can produce problematic nuclear fallout. Nuclear detonations produced high above the ground might not create mushroom clouds with a stem. When the detonation altitude is low enough, these afterwinds will draw in dirt and debris from the ground below to form the stem of the mushroom cloud.Īfter the mass of hot gases reaches its equilibrium level, the ascent stops, and the cloud starts flattening to the characteristic mushroom shape, usually aided by surface growth due to the decaying Turbulence. Physics ġ5-megaton Castle Bravo explosion at Bikini Atoll, March 1, 1954, showing multiple condensation rings and several ice caps.Īs it rises, a Rayleigh–Taylor instability is formed, and air is drawn upwards and into the cloud (similar to the updraft of a chimney), producing strong air currents known as " afterwinds", while, inside the head of the cloud, the hot gases rotate in a toroidal shape. Mushrooms have traditionally been associated both with life and death, food and poison, which made them a more powerful symbolic connection than, say, the "cauliflower" cloud. In 1946, the Operation Crossroads nuclear bomb tests were described as having a " cauliflower" cloud, but a reporter present also spoke of "the mushroom, now the common symbol of the atomic age". He wrote of the bomb producing a "pillar of purple fire" out of the top of which came "a giant mushroom that increased the height of the pillar to a total of 45,000 feet". ![]() Laurence, the official newspaper correspondent of the Manhattan Project, who accompanied one of the three aircraft that made the bombing run. On 9 September 1945, The New York Times published an eyewitness account of the Nagasaki bombing, written by William L. The atomic bomb cloud over Nagasaki, Japan, was described in The Times of London of 13 August 1945 as a "huge mushroom of smoke and dust". The Times published a report on 1 October 1937 of a Japanese attack on Shanghai, China, that generated "a great mushroom of smoke".ĭuring World War II, the destruction of the Japanese battleship Yamato produced a mushroom cloud. In 1930 Olaf Stapledon in his novel Last and First Men imagines the first demonstration of an atomic weapon "clouds of steam from the boiling sea. ![]() The 1917 Halifax Explosion produced a mushroom cloud. Lichtenberg stated to have later observed somewhat similar clouds, but none as remarkable. It was interpreted as an irregular meteorological cloud and seemed to have caused a storm with rain and thunder from a new dark cloud that developed beneath it. The cloud had been observed by legation counselor Lichtenberg a few years earlier on a warm summer afternoon. In 1798, Gerhard Vieth published a detailed and illustrated account of a cloud in the neighborhood of Gotha that was "not unlike a mushroom in shape". Mushroom cloud in an engraving from Gerhard Vieth's Physikalischer Kinderfreund (1798) The stabilization altitude depends strongly on the profiles of the temperature, dew point, and wind shear in the air at and above the starting altitude.Įarly accounts and origins of term The mass of gas plus entrained moist air eventually reaches an altitude where it is no longer of lower density than the surrounding air at this point, it disperses, drifting back down (see fallout). The buoyant mass of gas rises rapidly, resulting in turbulent vortices curling downward around its edges, forming a temporary vortex ring that draws up a central column, possibly with smoke, debris, condensed water vapor, or a combination of these, to form the "mushroom stem". Mushroom clouds result from the sudden formation of a large volume of lower-density gases at any altitude, causing a Rayleigh–Taylor instability. Some volcanic eruptions and impact events can produce natural mushroom clouds. They can be caused by powerful conventional weapons, like thermobaric weapons such as the ATBIP and GBU-43/B MOAB. The effect is most commonly associated with a nuclear explosion, but any sufficiently energetic detonation or deflagration will produce the same effect. Mushroom cloud from the atomic bombing of Nagasaki, Japan on August 9, 1945.Ī mushroom cloud is a distinctive mushroom-shaped flammagenitus cloud of debris, smoke and usually condensed water vapor resulting from a large explosion. ![]()
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