Radiation is the continual emission of infrared waves from the surface of all bodies, transmitted through space, without the aid of a material medium. Infrared radiation is absorbed by all objects and surfaces which experience a temperature rise. Infrared radiation is also emitted by all surfaces and objects which causes the temperature to fall. Generally, a good emitter of radiant heat (or vice-versa).
The rate at which energy is transferred by radiation depends on three factors: colour and texture of the surface, dull-black surfaces are better emitters of infra-red radiation than shiny-white surfaces; surface temperature, the higher the temperature of the surface of the object relative to room temperature, the higher rate of energy transfer; and surface area, if two objects have the same mass and are made of the same material, the object with the larger surface area will emit infra-red radiation at a greater rate.
