Resumen
Smith's (1969) analytical absorption spectrum of the atmosphere is incorporated in a thermodynamic model. This radiative formulation is applied to the infrared region. It computes separately the absorptivity by carbon dioxide and by water vapor, with a high wave length resolution, as a function of atmospheric pressure, temperature and gas content. The precipitable water or H2O content is computed using Adem's (1967) formula as a function of variables evaluated in the model: the surface temperature, the mid-tropospheric temperature and the horizontal extent of cloudiness. With this approach the model is able to simulate the positive feedback effect by long wave opacity of water vapor; that is to say its greenhouse effect. The computed spectrum for present values of CO2 and H2O concentrations shows good agreement with the estimates of Goody and Robinson (1951), Goody (1954) and Fleagle and Businger (1963).