Study Of Planetary Atmospheres Research Articles

Forbidden regions for the formation of clouds in a planetary atmosphere

Every model planetary atmosphere implicitly establishes unique altitude distributions for the saturation vapor pressures of its minor constituents solely by relating ambient atmospheric pressures and temperatures to altitude. It is therefore possible to determine for any model atmosphere the altitude regions where cloud formation due to condensation or sublimation of minor constituents is permitted or forbidden by basic thermodynamic laws, regardless of the amounts of the minor constituents present. As an example, this exclusion principle is applied to the formation of H2O clouds in the earth's upper atmosphere for conditions given by supplemental model atmospheres for latitudes 15° to 75°. The specific results presented permit inferences about the expected seasonal distribution of noctilucent clouds and serve generally to illustrate the application of a basic principle of thermodynamics to the study of planetary atmospheres.

On a Criterion Governing the Mode of Cloud Formation in Planetary Atmospheres

Abstract Condensation in vertically moving planetary atmospheric gases containing small quantities of any condensable vapor will occur in updrafts only if the latent heat of the viper is sufficiently large, otherwise the condensation will require adiabatic compression and will occur only in downdrafts, as first noted by Brunt. Several methods are presented for viewing and deriving a quantitative criterion for the intermediate case in which the vapor behaves in neutral fashion in either ascending or descending currents. Put in its most general form, relating the molar entropy of vaporization S of the condensable vapor and the molar specific heat Cp, of the carrier gas, the null criterion requires S= Cp. The peculiar nature of meteorological processes in a planetary atmosphere in which latent heat considerations imply downdraft condensation is examined in some detail, and some implications of the null condensation criterion for studies of planetary atmospheres and their evolution are discussed.

Physics at the National Research Council, Canada : Dr. G. Herzberg

DR. GERHARD HERZBERG has been appointed directer, Division of Physics, National Research Council, Canada, in succession to Dr. R. W. Boyle, who retired in October 1948. Dr. Herzberg is a Canadian citizen who has been on the staff of the Division of Physics for some months as a principal research officer, having gone to this post from the Yerkes Observatory, University of Chicago, where he had been professor of spectroscopy for nearly three years. During the preceding ten years, he was research professor of physics at the University of Saskatchewan, Saskatoon, Sask. Before that, he had worked in Germany at Darmstadt and Gottingen, and in the University of Bristol. Dr. Herzberg is a leading authority on spectroscopy and molecular structure, and is the author of three standard textbooks and numerous scientific papers. At Saskatoon he established a spectroscopy laboratory for graduate research and thus greatly strengthened the graduate school in physics and chemistry. He and his co-workers made important contributions to interpretation of data on spectral lines of distant stars and of comets. These investigations led up to his work at the Yerkes Observatory, where he built the world‘s longest multiple optical path (5,000 m. at atmospheric pressure) for the study of planetary atmospheres and to gain information on molecular structure. Using this equipment, he carried out important work on the infra-red absorption spectra of hydrogen, which has made it possible to detect hydrogen in planetary atmospheres. Dr. Herzberg will continue his varied researches in his new post.