Infrared radiation calculations are carried out by means of the emissivity method and by assuming that water vapor and carbon dioxide are the only radiatively active gases. (link.springer.com)
Since then, satellite reading of temperatures and the occlusion of numerous infrared bands, ground based, aircraft and balloon measurements of same, and an ever - increasing data base of the optical properties of CO2 (and other gases, like water vapour), have helped refine radiation calculations towards determining the atmospheric heat budget. (illconsidered.blogspot.ru)
The physics usually consists of advection, radiation calculations, surface fluxes (latent, sensible heat etc.), convection, turbulence and clouds. (realclimate.org)