Present-day desert environments - Climatic Change in Deserts - page 16

Figure 2.2. Seasonal migration of global wind systems and of the Intertropical Con-
vergence Zone (ITCZ). (Adapted from The Times Atlas of the World , Comprehensive
Edition , 1980.)
on chilled rock surfaces, especially the darker ones. This ephemeral dew allows some
desert antelopes and other small creatures to survive despite the lack of surface water.
Shortly before sunrise, small herds of gazelle may sometimes be seen licking the
dew from the surface of small piles of desert rocks in North Africa and Arabia, a
behavioural strategy that enables them to survive in otherwise waterless conditions.
The second major cause of aridity is a geographical location sufficiently far inland
to be away from the influence of moist maritime air masses. Rainfall decreases rapidly
away from the coast in all parts of the world except those close to the equator. Distance
inland is sometimes described as continentality and naturally applies to all big deserts,
including the great tropical deserts of Arabia, Australia and the Sahara. In the case
of these hot tropical deserts, the effects of continentality accentuate those of latitude.
Other examples of continental interior deserts are the great mid-latitude deserts of
central Asia, Mongolia and western China. Bitterly cold in winter, with temperatures