(a) Identify and explain any four factors which determine the direction of flow of ocean current (b) Using specific examples, discuss the effects of ocean c...

(a) Factors which determine the direction of flow of ocean currents

1. Prevailing (planetary) winds: steady winds such as the trade winds and westerlies drag the surface water along and set currents moving in their direction.
2. Rotation of the Earth (Coriolis force): the Earth's spin deflects currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, giving the circular (gyre) pattern.
3. Shape and position of land masses (coastlines): continents obstruct and deflect currents, forcing them to change direction and follow the coasts.
4. Differences in water density (temperature and salinity): cold, salty, denser water sinks and flows towards warmer areas, while warm lighter water flows on the surface, driving the direction of flow.

(b) Effects of ocean currents on the climate of adjacent coasts (with examples)

• Warm currents warm the coast and bring rainfall. The North Atlantic Drift keeps the coasts of north-west Europe (Britain, Norway) mild and ice-free in winter and gives rain. The warm Mozambique Current gives the south-east coast of Africa a warm, moist climate.
• Cold currents cool the coast and cause dryness/desert. The cold Benguela Current beside south-west Africa produces the arid Namib Desert and coastal fog; the cold Canary Current keeps north-west Africa dry; the cold Peru (Humboldt) Current produces the Atacama Desert on the west coast of South America.
• Where warm and cold currents meet (e.g. off Newfoundland where the warm Gulf Stream meets the cold Labrador Current) fogs form and rich fishing grounds develop.