Infrared Transmission of Synthetic Atmospheres* II Absorption by Carbon Dioxide

The total absorption ∫Aνdν has been determined for the CO2 bands at 15, 5.2, 4.8, 4.3, 2.7, 2.0, 1.6, and 1.4μ under stimulated atmospheric conditions. The absorber concentrations w ranged from 1 to 1000 atmos cm of CO2 for the strong bands and from 100 to 8600 atmos cm for the weak bands. Nitrogen was added to give total pressures ranging up to atmospheric; the pressure effects of oxygen were found to be similar to those of nitrogen. The observed data can be satisfactorily represented by two types of empirical relations.(1)For small values of total absorption,∫Aνdν=cw12(P+p)k;(2)For large values of total absorption,∫Aνdν=C+D Logw+K Log(P+p),where w is the CO2 absorber concentration, p is the CO2 partial pressure, and P is the total pressure. Values of the constants c, k, C, D, and K are given for each region of characteristic absorption. The present results are compared with those obtained in earlier studies. The use of the empirical relations in calculating atmospheric absorption is discussed.