(a) On an outline map of Africa, show and name (i) latitude 20°N (ii) the prevailing winds in July (iii) one cold oce current in the north (iv) one warm oce...

Answer Details

(a) On an outline map of Africa, show and name

• (i) Latitude 20 degrees N: a line drawn across the Sahara through southern Algeria, northern Niger, Chad and Sudan.
• (ii) The prevailing winds in July: the moist south-west monsoon (South-West Trade / South-West Monsoon) blowing onshore over West Africa from the Atlantic, and the South-East Trades south of the Equator.
• (iii) One cold ocean current in the north: the Canary Current, flowing south along the north-west coast (off Morocco and Mauritania).
• (iv) One warm ocean current in the south: the Mozambique/Agulhas Current, flowing south along the south-east coast (also the warm Guinea Current off West Africa).

(b) Effects of prevailing winds and ocean currents on the climate of one part of Africa

Taking the West African coast (Guinea coast):

• In July the moist South-West Monsoon blows onshore from the warm Atlantic and warm Guinea Current. It is laden with moisture, so as it rises over the land it brings heavy rainfall and gives the coast a long wet season, high humidity and moderate temperatures.
• The warm Guinea Current keeps coastal water and air warm and adds moisture, reinforcing the heavy rains.

By contrast, on the north-west (Saharan) coast the cold Canary Current cools the onshore air; the air holds little moisture and its lower layers are chilled, so instead of rain it produces fog and aridity, helping to keep the coast of Mauritania and the western Sahara dry and desert-like.