ABSTRACT
As we have seen in Chapter 2, the origin of the modern pattern of tropical climates dates from the early Miocene, when subtropical high-pressure zones and the arid climate conditions associated with these first appeared. The latitudinal zone lying between the subtropical high-pressure systems that occur at about 20°–30° now contains a variety of climates that lack the seasonally low temperatures of higher latitudes, but differ greatly in moisture regime (Figure 3.1). This low-latitude zone also comprises a special subsystem of the general circulation of the atmosphere, and most characteristics of the climate of any location within it can be traced ultimately to this circulation pattern. We therefore begin our consideration of tropical climates by describing the major characteristics of this atmospheric circulation.
