(energy transfer in the form of electromagnetic radiation)
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
are stellar models and models of Earthatmosphere,
particularly wavelengths at which it is opaque, i.e., wavelengths
not within atmospheric windows.