As captured by an automatic camera mounted on a nearby island, the Baker Day explosion at Bikini Atoll in Marshall Islands. The mushroom cloud that formed immediately after the explosion is obvious. (Image credit to Bettmann Archive/Getty Images).Energy is released randomly when a bomb explodes. Instead of an expanding ballof fire, nuclear explosions produce mushroom clouds.According to Katie Lundquist (a researcher in computational engineering at Lawrence Livermore National Laboratory, California), although the initial explosion of energy forms a sphere filled with hot air, it's not the end of the story. Hot air rises so the bulk of the sphere that contains the core of an Apple experiences more buoyancy than its edges.Lundquist explained that the way a sphere is formed, the largest column of low-density fluid is in the middle. This makes it rise the fastest, similar to the middle of a cupcake baking in the oven. Although we use the terms "fluid", "liquid" and "fluid" interchangeably in English, scientists can use the term "fluid," which can refer to either liquid or gas. According to Lundquist, both have a fluid-like shape and are capable of flowing.Related: How many atoms exist in the observed universe?Lundquist explained to Live Science that although the whole sphere rises, because the middle column is elevated with greater urgency the cooler air outside of the sphere "rushes in below the bubble which's rising".The rising bubble will then become a torus or doughnut shape. Hot air molecules are energized and move at high speeds, creating a lot of space between them. Lundquist explained that there's a "jet of material being sucked into vacuum that's pushing upward, and so that that forms the mushroom cloud at the top and the flatter area within the torus at the bottom." This jet that sucks up dirt, debris, and forms the stem of a mushroom, even as it feeds into its mushroom cap.This diagram illustrates the direction fluids travel after a nuclear blast. (Image credit: Wikimedia commons; (CC SA 1.0).Mushroom clouds are formed by nuclear bombs dropping during wartime. However, scientific experiments have shown that they can also form in space. Would a mushroom cloud form if the moon was nuked? Lundquist stated that the answer to this question is "no".She said, "They need an atmosphere to have that fluid material," like air. It's not possible to do it in a vacuum. The moon's atmosphere would not allow it to distort the initial sphere to form a torus. There would also be no air density difference to absorb the pillar of material and grow the cloud.There are many varieties of mushroom clouds, just like there are many species of mushrooms. The characteristics of the mushroom cloud will vary depending on its explosive yield and the height at the blast. Two main parts were required for explosions such as the one that occurred over Hiroshima, Nagasaki, Japan at the end of the second world conflict. The billows of cloud that grew from the condensing water and vaporized bomb products formed the first part. The second part consisted of a stem made up of brown material and other debris that extended from the ground. As you can see, the two parts didn't make contact.On August 8, 1945, the nuclear bomb was used to attack Nagasaki (Japan). (Image credit to Photo12/Universal Images Group via Getty ImagesLundquist stated that there is a "very distinct white cloud" and then a "brown below that." Because the bombs were nearly 2,000ft (610m) high, they did not touch the stem. They did not cause as much damage as later-made weapons. According to the U.S. Department of Energy, the bombs exploded with a force of 20 kilotons of NT or less. The yield of the Soviet Union's Tsar Bomba was 50,000 kilotons TNT.Lundquist stated that among the nuclear bombs tested, the stem and cap were the strongest and/or exploded nearer to the ground.Lundquist's lab colleagues and Lundquist study these effects in order to be able to predict the fallout accurately and provide guidance for consequence management to protect the public health in case of nuclear disaster.The threat of nuclear disaster is real. However, the combined arsenals of the entire world have nearly 10,000 nuclear weapons, down from more than 60,000 in the 1980s according to the Bulletin of the Atomic Scientists.Original publication on Live Science
