DO CLUSTERS CONTRIBUTE TO THE INFRARED-ABSORPTION SPECTRUM OF WATER-VAPOR

Many small bands found in experimental infrared absorption spectra of water vapor are not adequately described by traditional line profiles, even when empirical modifications to such profiles are employed. But these bands can be rather easily explained if they are attributed to intermolecular modes of water clusters including ion-induced clusters and, thus, are describable using simple oscillator models. Distributions of clusters in water vapor are discussed and related to experimental infrared spectra. Ionic activity in the atmosphere is discussed, including evidence suggesting that the fraction of clustered atmospheric water vapor increases with altitude thus altering present models of the earth's radiative transfer. It is concluded that the entire water vapor spectrum, expecially through the infrared continuum absorption region and the rotational band, should be carefully re-examined to determine which lines are best fitted by monomer models, and which by cluster models. © 1979.