Seymour L. Hess

SOME NEW MEAN MERIDIONAL CRQSS SECTIONS THROUGH THE ATMOSPHERE

Abstract Mean meridional cross sections along longitude 80°W are presented for summer and winter. The distributions of virtual temperature, virtual potential temperature, and geostrophic west wind are included. These sections represent an improvement over previous such efforts because they are based upon a longer period of observation, extend over a wider range of latitude, and are more nearly along a meridian. Certain new features of these cross sections are pointed out.

ATMOSPHERIC WAVES IN THE NORTHWESTERN UNITED STATES

Abstract I. The flow of air in vertical planes across the Rocky Mountains is studied through the potential-temperature distribution. Sinusoidal configurations of the isentropes are observed which seem to correspond to theoretical patterns, i.e., wide separation of isentropic surfaces (low stability) and ascent overlying descent in the lee with a nodal surface at 17,000-20,000 ft. This configuration is consistent with known distributions of chinook-arch clouds and hail. Another pattern with a very low nodal surface and a second node at 30,000 ft is found. The occurrence of this second pattern may be a function of high stability. The theoretical interpretation of these phenomena is discussed. II. A theoretically likely relationship between the development of lee troughs and migratory pressure waves is pointed out. The mechanism of cyclogenesis is demonstrated by mean maps giving the life history of lee-side development. This deepening depends upon the twofold effect of a Pacific low entering the west coast....

SOME ASPECTS OF THE METEOROLOGY OF MARS

Abstract After a description of the important observational facts for Mars, a discussion is given of the probable vertical structure of the Martian atmosphere based upon the ideas of radiative equilibrium in the stratosphere and near convective equilibrium in the troposphere. The proposed tropopause temperature is low enough to cause condensation of CO2 and thus may explain the blue clouds of Mars. Radiometric observations of temperatures on Mars are used to delineate the surface temperature field, and this is combined with cloud drift observations to define the circulation pattern. Considerable resemblance to terrestrial circulation is found, but differences exist and are discussed.

Dust on Venus

Abstract A calculation is performed of the friction velocity needed to lift dust from the surface of Venus. It is found that the most easily lifted grains are 16–17 µm in radius, and a friction velocity of about 1.3 cm s1 will suffice. These are much smaller values than on Earth and Mars. Very light free-stream winds will raise dust on Venus. Dust of this size cannot remain suspended in the constant-stress layer because gravitational settling is more efficient there than diffusion. The situation reverses at heights above 1–2 km where diffusion can keep fine dust suspended for long periods. A mechanism for production of fine dust is suggested.

Implications of condensation of carbon dioxide in the atmosphere of Mars

Abstract Some consequences of the report by Herr and Pimentel of a cloud layer of condensed CO2 at about 25 km in the atmosphere of Mars are examined. It is shown that this means the average lapse rate below the con- densation level is an appreciable fraction of the adiabatic value. It is shown also that condensation of CO2 implies almost inevitably that H2O condenses as well at a lower level.

A LABORATORY HURRICANE MODEL INCORPORATING AN ANALOG TO RELEASE OF LATENT HEAT.

Abstract The heat of neutralization between acid and base solutions may be used in laboratory models of atmospheric circulation to simulate the thermal effects of release of latent heat of condensation. This concept is used here to produce a model vortex strongly resembling a hurricane. An environmental acid solution is put in solid rotation; then a large-scale Hadley circulation is produced by cooling at the outer top boundary while a base solution is introduced at the bottom boundary. The low-level convergent flow containing the base solution is confined to an Ekman boundary layer. Little mixing and release of chemical energy occur until a suitably small radius is reached. At that point, vigorous ascent occurs with rapid cyclonic rotation. The result is strikingly like a hurricane eye wall. Descent in this eye is observed. Appropriate dimensionless parameters reveal that this interesting vortex is kinematically and dynamically similar to a steady-state prototype hurricane. Some conditions for the format...

A THEORY OF THE TEMPORAL AND LATITUDINAL DISTRIBUTION OF TEMPERATURE

Abstract An attempt is made to explain the observed distribution of mean temperature near the earths surface over latitude and through the year in terms of insolation, radiative processes, and large-scale atmospheric eddy conduction of sensible heat. The results are close to the observations and indicate that these three factors explain most of the observed distribution. The larger discrepancies are all explainable in terms of physical factors which were not included in the theory.