ABSTRACT
Large-scale atmospheric circulations are so complex and variable that mean flow patterns must be compiled if the general order of the atmosphere is to be examined. One of the dangers of the general circulation concept is that it is based upon statistical abstractions from the reality of instantaneous atmospheric circulations. The daily satellite coverage gives more direct evidence of secondary circulations than the general circulation of the atmosphere. The chapter examines the global scale space and time averages constructed from runs of satellite data. Many generally small-scale circulations arise in association with local modifications of the strength and direction of wind flow. Usually prompted by local topographic factors, such as relief, land/sea distributions and city morphologies, many tertiary winds are of considerable human and economic significance. There are many difficulties inherent in attempts to deduce mean circulations from monthly or seasonal cloud photographs, for many factors are involved other than cloud motion. However, some interesting regional differences are clearly indicated.
