Glossary

air burst: A nuclear explosion detonated at an altitude—typically, thousands of feet—that maximizes blast damage. Because its fireball never touches the ground, an air burst produces less radioactive fallout than a ground burst.

blast wave: An abrupt jump in air pressure that propagates outward from a nuclear explosion, damaging or destroying whatever it encounters.

direct radiation: Nuclear radiation produced in the actual detonation of a nuclear weapon and constituting the most immediate effect on the surrounding environment.

electromagnetic pulse (EMP): An intense burst of radio waves produced by a high-altitude nuclear explosion, capable of damaging electronic equipment over thousands of miles.

fallout Radioactive material, mostly fission products, released into the environment by nuclear explosions.

fireball: A mass of air surrounding a nuclear explosion and heated to luminous temperatures.

firestorm: A massive fire formed by coalescence of numerous smaller fires.

ground burst: A nuclear explosion detonated at ground level, producing a crater and significant fallout but less widespread damage than an air burst.

nuclear difference: Phrase we use to describe the roughly million-fold difference in energy released in nuclear reactions versus chemical reactions.

nuclear winter: A substantial reduction in global temperature that might result from soot injected into the atmosphere during a nuclear war.

overpressure: Excess air pressure encountered in the blast wave of a nuclear explosion. Overpressure of a few pounds per square inch is sufficient to destroy typical wooden houses.

radius of destruction The distance from a nuclear blast within which destruction is near total, often taken as the zone of 5-pound-per-square-inch overpressure.

thermal flash: An intense burst of heat radiation in the seconds following a nuclear explosion. The thermal flash of a large weapon can ignite fires and cause third-degree burns tens of miles from the explosion.