1. The study of all radiative processes affecting the earth's atmosphere. This discipline examines the absorption, emission, and scattering of electromagnetic radiation within the atmosphere; the nature and distribution of incident solar radiation at the top of the atmosphere; and the reflection and emission from the surface at the bottom of the atmosphere. The two main areas of importance of atmospheric radiation to meteorology are 1) the effect of radiative heating or cooling on temperature, thereby helping to define the basic structure of the earth's climate system, and 2) use of the spectral, angular, or polarization information content in measured radiation to deduce properties of the atmosphere or surface (i.e., remote sensing). See also solar radiation, terrestrial radiation. 2. Longwave radiation emitted by the atmosphere.