Mahikeng and Johannesburg show how altitude can affect temperature. Find them on the map on page 54. You can see that they are very similar except for altitude – Johannesburg is higher than Mahikeng, so Johannesburg should be colder. The table below confirms this.


Johannesburg Mahikeng


Mean monthly temperature (˚C) January 20 23


July 11 12


The table shows that Johannesburg’s temperature is 3° lower in January and 1° lower in July than that of Mahikeng.


The effect of ocean currents


Find Port Nolloth and Durban on the map on page 54. They are very close in latitude, and are both at sea level (same altitude). You would expect them to have very similar temperatures. But if you look at the table below, you will see that they do not.


Durban Port Nolloth


Mean monthly temperature (˚C) January 25 16


July 18 13


Durban is 9° warmer in January and 5° warmer in July than Port Nolloth. If you look again at the map, you will see there is a cold current off the coast at Port Nolloth and a warm current off the coast at Durban. These currents affect the temperature along the two coasts, causes Durban to be warmer than Port Nolloth.


The effect of distance from the sea Places that are very far from the sea are expected to be hotter in summer and colder in winter than places near the coast. Places far from the sea should have a big temperature range. Find Upington, Bloemfontein and Port Nolloth on the map on page 54. They are all at a similar latitude, but at different distances from the sea. Differences in their altitude will affect the temperature at each place, and the cold current at Port Nolloth will affect temperature there. However, altitude and the current will not affect the temperature range of each place. Look at the temperature data for Port Nolloth, Upington and Bloemfontein in the table below to compare the temperature range of these places.


Mean monthly temperature (˚C)


Port Nolloth Upington


Bloemfontein


January 16 28 23


July 13 14 8


Temperature range (˚C)


3


14 15


56 Module 3 Climate regions


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