On the Scale of Atmospheric Motions

Abstract

In a recent publication entitled The Dynamics of Long Waves in a Baroclinic Westerly Current1 (1947) the writer pointed out that, in the study of atmospheric wave motion, the problem of integration is greatly complicated by the simultaneous existance of a discrete set of wave motions all of which satisfy the conditions of the problem, namely that the motion be simple-harmonic and of a specified wave-length. Whereas only the long inertially-propagated waves are important for the study of large-scale weather phenomena, one is forced by the generality of the equations of motion to contend with each of the theoretically possible wave types. This extreme generality whereby the equations of motion apply to the entire spectrum of possible motions — to sound waves as well as to cyclone waves — constitutes a serious defect of the equations from the meteorological point of view. It means that the investigator must take into account modifications to the large-scale motions of the atmosphere which are of little meteorological importance and which only serve to make the integration of the equations a virtual impossibility.