The effect of factors affecting rainfall on places in South Africa


The amount of rainfall received in one year differs from place to place. What’s more, the season in which places get most of their rain also differs. The most important factors that affect rainfall in South Africa are latitude, relief and the temperature of the ocean currents. We will look at each of these factors.


The effect of latitude on rainfall in South Africa South Africa’s latitude affects both the amount of rain and the season in which it falls.


South Africa extends from about 22° to about 34° south. Look at the map on page 50. You will see that these are latitudes in which air mainly sinks, and so annual rainfall is not very high over most of the country. The sinking air is strongest in winter. In summer, when it is hot, air is better able to rise and therefore most of South Africa receives rain in summer. However, the southern part of the Western Cape is affected by the weather systems that move north from south of the country in winter. As a result, this part of the country gets rain in winter.


The effect of relief on rainfall


The mountains in the southern Cape and the escarpment form a barrier to winds blowing from the sea to the plateau. Find George and Beaufort West on the map on page 54. Notice that there is a range of mountains between them. Now look at the rainfall as shown in the table below.


Beaufort West George


Annual rainfall (mm) 296 721


You can see that George gets much more rain than Beaufort West. Clearly Beaufort West is in the rain shadow on the leeward side of the mountains, while George, on the windward side, gets rain.


The effect of ocean currents on rainfall


The cold current on the west coast and the warm current on the east coast suggest that less rain falls along the west coast than along the east coast. The rainfall figures for Port Nolloth and Durban prove this. Durban receives 1 038 mm of rain per year while Port Nolloth receives only 69 mm.


58 Module 3 Climate regions


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