Dispersion formula and continuous absorption of water vapor

Abstract

A full Lorentz line shape of the radiation absorption is used in order to account for the self-broadening continuum absorption of the water vapor. The Clausius–Mossotti formula of dispersion has been changed to take into consideration the influence of the medium on the imaginary part of the susceptibility. Absorption along path lengths is described by a hypothetical nonlinear equation. The method developed allows us to retrieve the supper-and sub-Lorentzian behavior of the continuum absorption of water in the region 700–1200 cm −1, the nonlinear density dependence of the water self-broadening continuum and then to model the strong temperature dependence of line absorption cross sections. An experiment by Burch and Alt (1984) is taken for a detailed consideration and a good coincidence of the data calculated and measured is observed. The extrapolation of the data from 700 to 1200 cm −1 is applied to the frequency and temperature dependence of the absorption coefficient in the transparency windows 2400–3000 cm −1, in a microwave region, and for a high pressure equal to 25 atm. The empirical temperature and pressure dependence of the interaction has been obtained. The selective continuum simulated is quite different from the conventional representation, especially, for the saturated spectra.