“…As a result of this extensive work, there is nearly unanimous agreement on the density depen-0169-8095/95/S09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI0169-8095(94)00028-0 dence (quadratic), general agreement on the temperature dependence (strong, negative, at least in the 8-13 fim window for atmospheric temperatures), but considerable disagreement as to the magnitude and physical mechanism responsible for the absorption. Water dimers (Penner and Varanasi, 1967), polymers (Carlon, 1981), collision-induced absorption (Birnbaum, 1985), and the superposition of the far wings of collisionally broadened allowed dipole lines (Elsasser, 1938) have all been suggested as possible sources of the water continuum. While the first two mechanisms are undoubtedly present and contribute to the absorption in the atmosphere (in varying amounts in the different spectral regions), there is increasing evidence to believe that they are not the primary mechanism.…”