Infrared absorption by molecular clusters in water vapor

New findings concerning clusters of water molecules in water vapor and in moist air are combined with observations from classical cloud physics to show that many discrepancies can be reconciled by the existence of enormous equilibrium populations of large neutral water clusters in the vapor state. These water clusters are believed to be those ’’nuclei’’responsible for the ’’cloudlike’’ condensation first described by Wilson at supersaturations of 4–5. They absorb electromagnetic radiation at infrared and longer wavelengths, and are believed to be responsible for the atmospheric infrared continuum absorption.