ABSTRACT
The large-scale wind circulation is subject to more or less regular seasonal shifts and changes of strength of its main features in response to the great changes of the heating pattern that accompany the migration of the zenith sun between about 23 ON and 23 aS. The circulation is also subject to apparently irregular shifts and changes on various time-scales: some of these account for the distinctive character of particular summers and winters or other seasons; others of much longer duration mark the character of a whole climatic epoch. In this chapter we shall study the tendencies that arise in the normal seasonal round of any year.
