Infrared Transmission of Synthetic Atmospheres* V Absorption Laws for Overlapping Bands

Although Lambert’s law Tν=e−kνw presumably applies to the absorption of gases in the infrared, the experimentally observed transmission Tν′ cannot be expressed by a simple relation of this type. It is observed, however, that in regions where the atmospheric carbon dioxide and water vapor absorption bands overlap Tν′(CO2+H2O)=Tν′(CO2) · Tν′(H2O) provided the total pressure P is constant. It is found that the total absorption ∫Aνdν for a synthetic atmospheric sample containing water vapor, carbon dioxide, and nitrogen can be expressed as ∫Aνdν=∫Aν(H2O)dν+∊∫Aν(CO2)dν, where ∫Aν(H2O)dν and ∫Aν(CO2)dν are given by the empirical relations obtained in earlier studies in the present series and ∊ is a fraction, which can be expressed in terms of the total absorption by water vapor.