Influence of Doppler Effect and Damping on Line-Absorption Coefficient and Atmospheric Radiation Transfer.

Abstract

The general term is given for the Taylor series and asymptotic expansions of the line-absorption coefficient when both the Doppler effect and damping contribute to the line shape. The influence of the Doppler effect on the fractional absorption of a line as measured in the laboratory is calculated and compared with the usual expressions which assume a Lorentz line shape. The radiation transfer in a planetary atmosphere is calcuiated when both the Doppler effect and damping contribute to the line shape and when the change of half-width with height is taken into account. It is shown that for the earth's atmosphere the radiative transfer calcuiated from the Lorentz shape alone is not changed appreciably by the Doppler effect for either weak or strong lines at heights up to at least 50 km, even at altitudes where the Doppler width is somethat greater than the Lorentz width.