Nuclear weapons fall into two categories; fission and fusion bombs. Fission bombs obtain their power from the splitting of uranium or plutonium atoms. This splitting of the atom is accompanied by a small pulse of energy. Fusion bombs are detonated by a fission device and obtain power by fusing together isotopes of hydrogen. The power of nuclear weapons is measured in megatons (M.T.), million tons of T.N.T.
What are the Effects of Nuclear Weapons?
If a nuclear weapon is detonated between 2000 - 50 000 ft above the ground it is known as an air burst. The bomb's energy is distributed as follows: 50% blast: 35% heat: 10% residual radiation (fallout dust) and 5% initial radiation. The moment the bomb is detonated there is a brilliant flash of light, brighter than the sun, and anyone looking at it would be temporarily blinded. Within microseconds the bomb parts are raised to a temperature of 10 000 000 oC and a fireball is formed. Almost immediately the surrounding air expands and forms a blast or shockwave which rushes into the vacuum formed by the fireball. If the fireball touches the ground dirt, dust and debris are swept upwards and form the characteristic mushroom cloud. The Initial radiation consists of neutrons, gamma rays, X rays and Ultra Violet light. Residual Radiation is the fallout dust formed in the mushroom cloud.
The unit of radiation is the Roentgen (named after the discoverer of X rays) which is the amount of energy needed to ionize 1 gram of air. Another unit is the RAD meaning Roentgen Absorbed Dose, and it refers to the radiation absorbed when it ionizes cell tissue in our bodies.
When referring to the effects of radiation we speak of an LD-50 dose. This is the amount of
radiation that would kill 50% of all people exposed to it.