ABSTRACT
The most important balanced wind is the geostrophic wind in the ‘free atmosphere’ above the shallow ‘friction layer’ overlying the surface of the earth, geostrophic approximations are often close to reality. This fact has long been basic to upper level climatology and meteorology. Positive vortices encourage vertical cloud growth and associated weather; negative vortices encourage subsidence and low sheet clouds and/or inversions near the surface of the earth. Against this, maps of atmospheric pressure are difficult to subdivide into areas of high and low pressure because of the subjective nature of the process of choosing a suitable boundary value. The ground methodological work has been undertaken principally by V. E. Suomi and his coworkers in the University of Wisconsin utilizing movie film loops of Applications Technology Satellites spin-scan camera pictures. The film loops not only illustrate cloud motion generally, but also permit the separate identification of upper- and lower-level air flow patterns through the differential movements of their visible tracers.
