Prompt radiation includes ionizing radiation from the nuclear reactions in the warhead and decay of fission products left by the explosion. These radiations, particularly neutron radiation, are significantly attenuated by the atmosphere for low altitude bursts. For explosions above most of the atmosphere, ranges of prompt radiation effects are greater than for atmospheric bursts.
Several effects are relatively unique to high altitude bursts:
- Electromagnetic pulse (EMP) is important only for high altitude bursts. For such detonations, ionization of the upper atmosphere can produce a brief intense pulse of radio frequency radiation which can damage or disrupt electronic devices. For explosions above most of the atmosphere, EMP can affect large areas.
- Ionization of the atmosphere from explosions in the atmosphere can interfere with radar and radio communications for short periods.
- Charged particles produced by explosions above the Earth's atmosphere can be captured by the Earth's magnetic field, temporarily creating artificial radiation belts that can damage spacecraft and injure astronauts/cosmonauts in orbit.