radiative transfer

Radiative transfer is the transfer of energy via electromagnetic radiation (EMR) through a gas or plasma, in particular, for a gas not so transparent that EMR merely misses all impediments. For such a less-than-transparent gas, absorption, emission, and scattering by the constituent particles (e.g., atoms) are basic to the process, the energy's overall movement being the aggregation of the small amounts of energy moved by individual photons between individual particles. The common method of analyzing and describing radiative transfer (radiative transfer model) is to consider the resulting radiance (aka intensity), the rate of energy flowing at a given time through a given area at a given location. Spectral radiance is the radiance at a given wavelength. An equation of radiative transfer (RTE) is devised to characterize the process, relating the transmission of energy to quantities that characterize the likelihood of absorption, emission, and scattering.

Two areas of science in which radiative transfer is relevant stellar models and models of Earth atmosphere, particularly wavelengths at which it is opaque, i.e., wavelengths not within atmospheric windows.