Abstract
A statistical theory, with a simple model for intermolecular potentials, is used to calculate the absorption of infrared waves by the far wings of water vapor rotational transitions. The model is similar to ones that have been used to explain the second virial coefficient. The effectiveness of self-broadening relative to broadening by nitrogen is found to increase with frequency displacement from the center of the rotational band and to decrease with temperature, in agreement with the observed characteristics of water vapor.