Thermal emittance
= Thermal emittance
{wiki=Thermal_emittance}
Thermal emittance, often referred to simply as emittance, is a measure of a material's ability to emit thermal radiation. It is defined as the ratio of the amount of thermal radiation emitted by a surface to the amount emitted by a perfect black body at the same temperature. A perfect black body has an emittance of 1, meaning it emits the maximum possible radiation for a given temperature.