Most practical applications require an assessment of the accumulated effect of many interactions not just that of a single interaction that has so far been the focus of much of the research discussed above. Whereas studies of the intrinsic radiative properties of the atmosphere provide the foundation of much of the more applied research described below, radiative transfer is the mechanism connecting the basic and applied aspects of the science.
Radiative transfer has a long and varied history and much of the developing theory is common to other topics of transport theory. Radiative transfer when applied to a single dimensional medium is well understood and simple approximations (such as the two-stream approximation [e.g. Harshvardhan and King, 1993] and the diffusion approximation) exist to provide a description of the radiative transfer over much of the representative parameter space. The most recent advances of one dimensional atmospheric radiative transfer is in the calculation of the fully polarimetric radiance fields stimulated by our renewed interest in the polarization of atmospheric radiation [ Takano and Liou, 1993; Evans and Stephens, 1991; Mishchenko et al., 1994].