Sunday, 29 July 2012

Why does a mushroom shaped cloud form after a nuclear bomb explosion?

When a nuclear weapon explodes,there is a rapid release of a large amount of energy within a small volume.This results in significant increase in temperature and pressure.The temperature may be a few tens of million degrees and pressure a few million times the atmospheric pressure.At this temperature,all the material present in the weapon will be converted into hot compressed gases.
Within a fraction of a millionth of a second of the explosion, the weapon's residues emit large amounts of energy mainly in the form of X-rays.The surrounding atmosphere absorbs this energy.This results in the formation of a blazzing, highly luminous, spherical mass of air and gaseous weapon residue called the fireball.
             Within an extremely short time after the explosion,the fireball from a high yield nuclear weapon will be about 130 meters across increasing to about 1700 meters in ten seconds.The fireball expands rapidly engulfing the surround air.
             The ball of hot air is less dense than the surrounding air.It rises swiftly like a hot air balloon.This rising column pulls up debris of the weapon,dust and moisture along with it forming cloud.As it moves up,it cools gradually and reaches about 10km where the atmosphere is extremely stable.The ball of air mass moving up does not have enough energy to penetrate this stable layer.It flattens out.As the relatively warmer layers at the bottom push up,the top layer spread laterally and equally in all directions and the cooler denser layer descend at he edges,giving a distint mushroom shape.

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