Below     40°     south     latitude,     the     climate     is progressively drier and cooler. However, the extreme southern tip of South America is characterized by year round cold and damp climate due to a strong maritime influence. West Coast Climate The West Coast, from northern Peru to the middle of  Chile,  is  a  desert.  North  and  south  of  this  desert midsection, the climate is quite humid. The northwest coast has a typical tropical climate with wet and dry seasons. Below  central  Chile,  the  climate  again  shows  a typical Southern Hemisphere seasonal reversal of that found in North America. The weather in this region is similar to that found along the northwest coast of North America.  The  climate  is  generally  rainy  and  cool. Summer  does  not  seem  to  exist  as  we  know  it.  Yet, winter temperatures average above freezing. AFRICAN WEATHER Africa’s   climate   is   unlike   that   of   any   other continent for several reasons. The most important is the fact that the entire continent is within the tropical zone. The equator bisects the continent; therefore, in the area north and south of the equator, the climates are similar, yet they differ because the region north of the equator is much   larger   than   the   southern   region.   Since   the northern  area  is  so  broad  in  the  east-west  direction, maritime effects inland are minimal. Also, an extensive low-pressure area develops inland due to extreme land mass heating. A belt of high pressure, however, with its maritime  influences  dominates  the  southern  section, during winter and by low pressure during summer. Another  factor  is  the  cold  currents,  which  exist along its western shores. These currents allow an influx of cool winds and associated weather to the West Coast. The  final  factor  involves  the  lack  of  high  mountain ranges common to other continents. Since there are no prominent  mountain  ranges,  the  various  climate  types in Africa blend together, showing no sharp distinctions. The  most  important  climatic  element  in  Africa  is precipitation. Precipitation is greatest near the equator (60  to  80  inches  to  over  120  inches  in  places).  It decreases sharply to the north (less than 10 inches), and decreases gradually south of the equator (average of 20 to 40 inches). Because Africa is in the tropical zone, the precipitation belt of the intertropical convergence zone (ITCZ) moves with the seasons. This belt of precipitation   moves   northward   in   the   summer   and southward   in   the   winter.   Africa   does   have   distinct climatic  regions.  Air-mass  movement  and  influences allow for a division of eight climatic regions. Northern Region The   northern   region   includes   the   great   Sahara desert.    The    desert    is    a    source    region    for    dry continental-type  air  masses.  While  maritime  air  may transit the area, the air masses are highly modified and often    exhibit    continental    properties    after    moving inland.  This  desert  region  is  extremely  hot  during  the day throughout the year but is very cool at night due to a lack of moisture; hence, strong radiational cooling. Southwestern Region The  southwest  region  is  an  arid  to  semiarid  area, which is known as the Kalahari Desert. The temperatures   are   not   as   extreme   as   in   the   Sahara because the land area involved is much smaller. North Central Region The north central region is a semiarid area located along  the  edge  of  the  Sahara.  While  the  temperatures are similar to those of the neighboring desert (50°F in winter   to   well   above   80°F   in   summer),   this   area occasionally gets precipitation in the winter. The source of this precipitation for the northern area is maritime air from  the  Mediterranean;  in  the  south,  it  is  the  spotty rainfall provided by the meandering ITCZ. Sub-Equatorial Region The   sub-equatorial   region   extends   toward   the equator  from  the  semiarid  region  in  the  north.  The region  is  marked  by  seasonal  rainfall  associated  with the position of the ITCZ. The region is wet for about 5 months (Nov-Mar), and dry during the rest of the year. Temperatures  show  little  seasonal  variation  (68°F  to 86°F)  because  of  the  close  proximity  to  the  equator. The only exception to this temperature stability occurs in  the  western  portion  which,  during  the  winter,  is occasionally   influenced   by   cool   weather   from   the north. Equatorial Region The equatorial region includes the southwest tip of northern  Africa  and  the  region  between  5°  north  and south  latitudes,  extending  from  the  western  coast  to Lake  Victoria.  It  is  the  wettest  climate  in  all  Africa. 6-29