2.关键术语 2.1.1.9 Blackbody A blackbody is an ideal thermal emitter that transforms heat energy into radiant energy with maximum rate permitted by thermodynamic laws.Any real material at the same temperature cannot emit thermally at a rate exceeding that of a blackbody. Likewise,a blackbody must absorb and convert all incident radiant energy into heat energy regardless of the spectral band of the radiant energy (Colwell et al.1983). 9 2.1.1.14 Gray Body A gray body is a hypothetical source that would radiate as a blackbody but with an emissivity lower than unity and constant with wavelength.The gray body assumption is more useful as a first approximation to the actual emission of a real object or medium than is the ideal blackbody radiation.It is used in radiative transfer problem,for instance,in planetary atmospheres(Colwell et al.1983). 电寸