NEAR-INFRARED LIGHT SCATTERING BY TERRESTRIAL CLOUDS

Abstract

Calculations of the reflectivity of water clouds (liquid and ice particles) are compared to observations of terrestrial clouds in the near infrared. Results indicate that it is possible to use the spectral variation of the reflectivity to derive the size of the cloud particles and their phase (liquid or solid) as well as the total optical depth of the clouds. Typical results show dense cirrus clouds to have an optical depth of greater than or equal to 10 and to be composed of ice particles of mean radius 15 to 20 U; the cumulus clouds which were analyzed showed a more variable, butusually smaller, particle size. It is found that most of the gas absorption takes place within the clouds rather than above them.