Infrared Absorption Spectra Attributed to Ion-Nucleated Water Clusters
Abstract
Until recently, it was assumed that atmospheric water was found in one of three phases: vapor (monomer), liquid droplets or ice crystals. Now it is known that an ion-nucleated, polymolecular cluster phase of water exists in the vapor phase, as well. These water clusters consist of numbers of water molecules gathered about small ionic nuclei, where the number of molecules per cluster is dependent upon relative humidity and other meteorological parameters. In real atmospheres, mean cluster sizes range from about 11 to about 14 molecules per cluster. Their infrared absorption is due to intermolecular hydrogen bonding, and the 'continuum'-like absorption spectrum which they produce is shifted in wavelength by changes in mean cluster size. Water clusters are always present in the atmosphere and in the cleanest of laboratory experimental equipment. Except under supersaturations of about 420% relative humidity, clusters are not able, because of equilibrium considerations, to attain 'critical' size and to grow to droplets. Water cluster theory and equations give excellent agreement with observed data for infrared 'continuum' absorption.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1977
- Accession Number
- ADA044661
Entities
People
- Hugh R. Carlon
Organizations
- United States Army Armament Research, Development and Engineering Center