Common ocean currents

The planetary wind system plays an important role in the creation of the
oceans’ surface currents. In general, these currents follow the enormous
circulation loops around the oceans, delevering a huge supply of heat from
the equator to high latitudes. Most of the currents’ heat is lost along the
western boundaries of oceans, so that time they make their return journey
along the eastern boundaries they are cold.
The coastal deserts of Africa and South America owe their existence to this
phenomenon. For example, the Namib Desert (see illus., p. 18) on the western
coast of southern Afric a is washed by the cold Benguela current. Cold air
holds very little moisture. So the Namib receives little rainfall
Occasionally the circulation of the oceans’ surface currents is reversed. El
Nino which occurs every five to eight years, reverses the usual pattern of
currents in the South Pacific. The results include severe drought in Australia
and heavy rains and floods in the western countries of South America