ABSTRACT
This chapter focuses on a somewhat incomplete understanding of all the physical processes and interactions that govern the climate of deserts. If human activities, therefore, are altering the size of deserts and their margins, climatic changes could influence more than just the immediate region involved. The deserts occur primarily because the large-scale circulation subsystems of the atmosphere are either unable to transport much moisture to them, or they are unable to sustain the processes that can release the atmospheric moisture in the form of precipitation. Atmospheric motion, or circulation, then, is a crucial factor in the existence of these major deserts. Deserts are situated where the large-scale global circulation patterns either deny moisture to a region or where subsiding air associated with those patterns puts a lid on rain-producing convection. Vertical stability is determined by the vertical distribution of temperature and moisture in the air mass over a region.
