Heat Transfer - Radiation

Every object emits electromagnetic radiation in a wave spectrum related to its own temperature. An object cooler than its surroundings will absorb more energy in the form of radiation than it emits. This radiation can pass through both free space and transparent media. Heat transfer by radiation helps sustain life on Earth—energy received from the Sun is an example of this process.

The electromagnetic radiation associated with heat transfer is sometimes referred to as blackbody radiation (where "blackbody" is an ideal emitter and absorber) or as thermal radiation. Thermal radiation is often associated with infrared radiation, although more thermal energy is received from the visible potion of the Sun's spectrum than from the infrared portion.