The explosion of a nuclear weapon gives rise to a variety of powerful phenomena. This selection influences an interaction of the initial energy of the explosion with its environment and consequently ratio between the forms in which the energy is transmitted. Weather conditions are also important: fog can limit thermal radiation, wind can distribute fallout-particles.

           In a fission explosion, the components of the weapon rapidly rises to temperatures of several tens of millions degrees,  the temperature of chemical explosion are at most some five thousand degree Celsius. All the matter became gasified within the approximate volume of the original weapon; thus immense pressures are created. Within a million of a second, huge amount of X-ray energy are release and absorbed by the atmosphere, forming a hot, luminous mass of fireball. Observers of early tests noted that a 1 MT fireball appeared several times brighter than the sun from over 50 miles (80 km) away. The fireball now rapidly grows and rises. In about a minute a 1 MT fireball rises over 4 miles (6.5 km); during this process gases condense again to form particles. If the weapon is close enough the surface, the updraft will pull debris up into the radioactive cloud this will be a mixture of debris, water from the atmosphere and fission products from the weapon itself. If 1% from a MT weapon is enabled by low altitude of the fire ball to vaporize matter on the ground, some 4000 tons of material will be added to the cloud, leaving a crater .The equivalent pickup of water over the seas or lakes would be some 20 000 tons. This is the source of radioactive fall-out, distribution of which will then be determined by the direction and speed of wind. Early fall-out of visible particles is usually complete in 24 hours; this local fall-out is succeeded by delayed fall-out, which may occur worldwide.

            Immediately after the explosion, shock wave of compressed air moves rapidly out, traveling (4.8 km) in the first 10 seconds: in 50 seconds it travels 12 miles (19.3 km), still moving faster than sound. A secondary blast wave cause by reflection of the first is also very powerful. Where the two waves meet occur the highest "over-pressures"; after an explosion at 6,500 feet, a 1 MT bomb will produce this in a circle roughly 1.3 miles from the ground zero (i.e. the point directly under the explosion). At this point the over-pressure would be about 16 lb/sq. in or twice normal atmospheric pressure. Transient winds will reach velocities of hundreds of miles an hour.

            The weapon also emits thermal radiation; Individuals may suffer burns up to 12 miles from 1 MT weapon. In addition, various nuclear radiation occur. The fission process emits neutron and gamma rays; This is so-called prompt radiation, from the actual explosion. Further gamma and beta radiation emerges from the decay of radioactive articles. The fusion portion of the weapon uses chiefly neutrons.

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