Absorption

(1) Process of taking in and being made part of an existing amount of matter. (2) Interception of electromagnetic radiation or sound.

Atmospheric absorption is defined as a process in which solar radiation is retained by a substance and converted into heat energy. The creation of heat energy also causes the substance to emit its own radiation. In general, the absorption of solar radiation by substances in the Earth's atmosphere results in temperatures that get no higher than 1800 degrees Celsius. According to Wien's Law, bodies with temperatures at this level or lower would emit their radiation in the longwave band.