VARIATIONS IN EMISSION-SPECTRA FROM WARM WATER FOGS - EVIDENCE FOR CLUSTERS IN THE VAPOR-PHASE

The ability of water to form molecular aggregates or clusters by hydrogen bonding is believed to be responsible for its unexplained spectral emission and absorption in many wavelength regions including the infrared. Data from 442 spectroradiometer observations of steam clouds and warm water fogs in the 7-13 μm infrared atmospheric 'window' region are summarized, and evidence is presented for cluster activity in the vapor phase. Observations show agreement with theory relating infrared absorption and emission to intermolecular vibrations in distributions of water ion clusters with mean sizes of 10-13 molecules per cluster. Clusters are implicated not only in infrared 'continuum' absorption of water vapor in the atmosphere, but in ionic activity affecting seemingly diverse phenomena such as cloud nucleation and the electrical conductivity of moist air. © 1979.