The Theoretician’s Clouds—Heavier or Lighter than Air? On Densities in Atmospheric Thermodynamics

Abstract

hreefold densities may be introduced into atmospheric thermodynamics. For rainless clouds the general indirect or implicit conclusion is that they are denser than moist air under the same circumstances, although in a classic treatise a different conclusion was reached, to the effect that cloudy air (containing water and/or ice) is less dense than moist air under the same pressure and temperature. By reconsidering carefully different ways of determining densities, any doubts that may linger after reading the scant literature dealing explicitly with the density of a cloud are dispelled.