Any atmospheric, surface, or shallow subsurface burst. If it is too high to entrain dirt or water then the cloud is composed entirely of material from the bomb itself.
fallout, a mixture of debris picked up by the updraft in the mushroom cloud and condensed vaporized bomb materials.
Any explosion exposed or vented to the atmosphere. The bigger the explosion the bigger and more well formed the mushroom cloud.
== == Any thermonuclear device creates a mushroom cloud because of the immense heat. Any explosion can create a mushroom cloud, as long as it can heat the gases enough to allow them to rise. The rising air lifts off the ground rapidly, until it reaches a height where the other gases are more dense. The falling gases then get sucked back into the "stem" as the rising gases are moving rapidly enough to create a vacuum. The "mushroom" phenomenon is created whenever there is a density differential between two bodies of fluid, called a "Rayleigh-Taylor Instability". This is mathematically dictated by Navier-Stokes equations.
The force of the explosion pushes the air out from around it, creating a pocket of low air pressure. As the smoke and debris cloud begins rising, fresh air flows in from outside the area of explosion, forcing the cloud higher and forming the shape of a mushroom. This can happen with any sufficiently powerful explosion, but it's most well known and most well associated with nuclear explosions.
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. When a nuclear device is exploded, a large fireball is created. Everything inside of this fireball vaporizes, including soil and water, and is carried upwards. This creates the mushroom cloud that we associate with a nuclear blast, detonation, or explosion. Radioactive material from the nuclear device mixes with the vaporized material in the mushroom cloud. As this vaporized radioactive material cools, it becomes condensed and forms particles, such as dust. The condensed radioactive material then falls back to the earth; this is what is known as fallout. Because fallout is in the form of particles, it can be carried long distances on wind currents and end up miles from the site of the explosion. Fallout is radioactive and can cause contamination of anything on which it lands, including food and water supplies. A nuclear detonation creates a severe environment including blast, thermal pulse, neutrons, x- and gamma-rays, radiation, electromagnetic pulse (EMP), and ionization of the upper atmosphere.
A low altitude detonation or a groundburst will cause a crater to form. Nuclear detonations that take place near the ground (but not underground) will create a mushroom cloud (this is caused by a Raleigh-Taylor instability). I have noted that a lower level detonation close to the ground will suck up material into the fireball and create a more pronounced stem.
to create a mushroom cloud take a mushroom put it in the mirowave in for 30 mins and their you have it...A MUSHROOM CLOUD by, bob and larry. 2009
A mushroom cloud is a distinctive pyrocumulus mushroom-shaped cloud of condensed water vapor or debris resulting from a very large explosion. They are most commonly associated with nuclear explosions, but any sufficiently large blast will produce the same sort of effect. Mushroom clouds are formed by many sorts of large explosions under earth gravity, though they are best known for their appearance after nuclear detonations. Inside a mushroom cloud: cooler air is drawn into the rising toroidal fireball, which itself cools into the familiar cloud appearance.
Any: conventional, nuclear, or impact can cause a mushroom cloud.
An airburst, surface burst, or shallow subsurface burst. If the burst is too high to entrain dirt or water the cloud will be composed entirely of material from the bomb itself.
mushroom cloud
No
A nuclear detination
Many nuclear detonations will create a mushroom cloud (especially near the ground due to material from the ground being sucked up into the vacuum created by the explosion, thus forming a large part of the "stem" of the cloud) and if they are near the ground, will create at least a small crater, but it sounds like you are talking about a groundburst detonation (as opposed to an airburst). These types of explosions carry more radioactive debris from the ground into the air and generate a lot of fallout due to the irradiated debris from the explosion.
A mushroom cloud is the product of a very large explosion, such as from the detonation of a nuclear weapon. The cloud itself is formed by the rapidly rising ball of hot gasses.
Francium is an element, it does not 'create' anything.
Surface burst