Unit 2 - Climate Regions

Question 1

Name and describe the 7 factors influencing rainfall.

Answer 1

1. Temperature affects rainfall
   High temperatures are necessary in order for evaporation to take place, while cooling of humid air is necessary for condensation to occur.
2. Mountains affect rainfall
   Windward side of mountains (side facing oncoming wind) experience higher rainfall than the leeward side (side of mountains not exposed to wind). Known as orthographic effect.
3. Ocean currents affect rainfall
   Warm ocean currents increase evaporation and rainfall, while cold ocean currents limit evaporation.
4. Winds affect rainfall
   Winds blowing from the sea towards the land are known as onshore winds. They feed moisture to the land. Offshore winds on the other hand, are dry, with no chance of rain.
5. Latitude affects rainfall
   It rains more n sr the equator than in the regions further away from the equator. Another reason why there is likely to be more rain near the equator is that it is hotter there. Where there is more heat, there is also more evaporation taking place.
6. Altitude affects rainfall
   Rain occurs more frequently in areas in higher altitude than in low altitudes. In general, as altitude increases, rainfall increases and temperature decreases. The increasing altitude causes the air to cool and if it cools enough, condensation will occur, forming clouds and sometimes resulting in precipitation.
7. Distance from the sea affects rainfall
   It rains more on the coast than inland. Seas are a source of humidity.
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Question 2

Name the different climate regions.

Answer 2

Coastline
Indian Ocean lies to the east of South Africa & the Atlantic Ocean to the west. Only ideal natural harbor along the coastline is Saldana bay on the west coast.

Relief
SA has 2 distinct surfaces: interior plateau, and the land between the plateau and the coast. Boundary between 2 areas in known as the great escarpment. It’s height above sea level varies from 1500m in the south west of the country (roggeveld) to the height of 3482m in the drakensberg mountains, situated in kzn

Currents
Cold Benguela current sweeps up from the Antarctic along the Atlantic coast, laden with plankton and providing ample fishing. The east coast has the north-to-south Mozambique current to thank for its warm water. Further down-coast, the agulhas current plays a warming role.

These 2 currents have a major effect on the country’s climate. The east coast with the warm current provides evaporation and consequently generous rainfall in Durban and a large part of KZN. It is interesting to note the difference in temperature between port nolloth on the west coast, and Durban on the east coast.

Climate
SA is classed as semi-arid; however country has considerable variation in climate- more so than other countries in sub-Saharan Africa. Also tends to have lower average temperatures than other countries situated at similar latitudes across the world.

Rainfall
SA has an average of 464mm of rain per year, which is lower than world average of 860mm. Western cape region east is only region that has winter rainfall. Rest of country generally has summer rainfall.

Temperature
Interior plateaus altitude ensures that average summer temperatures stay below 30°. In winter, for same reasons, nighttime temperatures drop to freezing points.

Question 3

Name the 4 rainfall regions.

Answer 3

1. Dry regions
   Fact that largest part of country experiences summer rainfall doesn’t mean our country isn’t dry. SA has lower-than-average rainfall compared to rest of world. Large part of SA classified as dry. Convection rain (isolates thundershowers) brings some relief to driest areas, but is erratic.
2. Summer rainfall regions
   Largest area rainfall area in SA is the summer rainfall area. Occurs mostly from October to February. South-east winds move moisture into interior. Condensation occurs, followed by formation of huge cumulonimbus clouds. Thunder and lighting usually accompany a short intense burst of rain (convection rain). Erosion is common in areas where these showers occur, as the rain falls hard and fast, and does not have time to seep into the ground. Crop damage could take place in some instances.

Eastern half of SA is far wetter than western half.

3. Winter rainfall region
   Only found in the south-western part of SA and includes Cape Town. Rainfall region extends from olifants river in the northwest, to breë river in south. Type of rain falling is cyclonic rain (soft persistent rain) and falls from May to August.
4. Rain all year round
   Have region from Breede river to port Elizabeth, experiences rain all year round. Belt runs further up coast into KZN but, rain there is mostly classified a summer rain, though does sometimes fall in winter. Condensation occurs, clouds form and result is relief (orographic) rain on seaward side of escarpment.