Radiation

Energy transported through electromagnetic waves. These waves do not need molecules to propagate them, and in a vacuum they travel at nearly 300,000 kilometers per second. See shortwave radiation and longwave radiation.

Energy transfer in the form of electromagnetic waves or particles that release energy when absorbed by an object. See ultraviolet radiation, infrared radiation, solar radiation, longwave radiation.

Energy emitted in the form of electromagnetic waves. Radiation has differing characteristics depending upon the wavelength. Because the radiation from the Sun is relatively energetic, it has a short wavelength (ultra-violet, visible, and near infrared) while energy radiated from the Earth's surface and the atmosphere has a longer wavelength (e.g., infrared radiation) because the Earth is cooler than the Sun. See ultraviolet radiation, infrared radiation, solar radiation, longwave radiation, terrestrial radiation.

Radiation 1) Emission or transfer of energy in the form of electromagnetic waves. 2) The process by which electromagnetic radiation is propagated through free space by virtue of joint undulatory variations in the electric and magnetic fields in space. This concept is to be distinguished from conduction and convection.

(RAY-dee-AY-shun) Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).

(RA'-de-ay'-shun) energy transmitted by waves through space or through some medium' usually referring to electromagnetic radiation when used without a modifier.

(ray-dee-AY-shin): The emission of energy in waves or particles. Often used to treat cancer cells.

Energy transmitted through space as waves or particles.

Electromagnetic energy, and particles moving close to the speed of light.

The transfer of heat through matter or space by means of electromagnetic waves.

Energy emitted in the form of rays, waves, or particles by the atoms and molecules of a radioactive substance as a result of nuclear decay.

Energy transport through electromagnetic waves. See shortwave radiation and longwave radiation.

(1) The emission and propagation of waves transmitting energy through space or through some medium; for example, the emission and propagation of electromagnetic, sound, or elastic waves. (2) The energy transmitted by waves through space or some medium; when unqualified, usually refers to electromagnetic radiation. Also known as radiant energy. (3) A stream of particles, such as electrons, neutrons, protons, alpha particles, or high-energy photons, or a mixture of these. (See Ionizing Radiation, Nuclear Radiation, and Thermal Radiation.)

In communication, the emission of energy in the form of electromagnetic waves. 2. The outward flow of energy from any source in the form of radio waves. [NTIA] [RR]