asslam o alaikum seniors! plz check my notes and guide me as i m a new comer and i even dont know how to answer a question in geography becoz i hv no background for geography.............and tell me that how much lengthy should be the answer...........


Q: Define and discuss the origin of ocean currents. Explain the Ocean currents of Atlantic Ocean.

Ocean Current:
An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow. There are many factors that determine the strength of a current, as well as the route it will follow. Winds have the most important influence on the flow of currents, but tides, precipitation, evaporation rates, shape of the ocean floor, and inflow from rivers and adjacent seas are also important.

Factors that cause Ocean Currents:
1. Solar Heating
2. Power of Winds
3. Force of Gravity
4. The Coriolis force
5. Land masses

Types of Ocean Currents:
There are two type of Ocean Currents:

1.Surface Currents:
Surface ocean currents are generally wind-driven and develop their typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the Southern hemisphere because of the imposed wind stresses. These waters make up about 10% of all the water in the ocean and are the upper 400 meters of the ocean.

2.Deep Water Currents:
These currents flow under the surface of the ocean and make up the other 90% of the ocean. They are driven by density and temperature gradients. These deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase.

Importance of Ocean Currents:
Ocean currents can flow for great distances, and together they create the great flow of the global conveyor belt which plays a dominant part in determining the climate of many of the Earth’s regions. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude.

Currents of Atlantic Ocean:
The Atlantic ocean is the second-largest of the world's oceanic divisions. With a total area of about 106,400,000 square kilometres (41,100,000 sq mi), it covers approximately 20% of the Earth's surface and about 26% of its water surface area. The Atlantic is divided into the North and South sections by the Equator and is connected to the larger Pacific Ocean via the Arctic Ocean to the north, and by the Drake Passage to the south. Circulation of surface waters is generally clockwise in the North Atlantic and counterclockwise in the South Atlantic. There are, however, many exceptions to the general circulation, particularly along the coasts.

North Atlantic Ocean:
In the North Atlantic, the strongest current is the warm Gulf Stream, which forms in the Gulf of Mexico. It flows northeastward off the United States coast, encounters the cold Labrador Current from the north, and continues across the Atlantic as the North Atlantic Current, or Drift. It continues northward as the Irminger and Norwegian currents.
West of Spain, part of the North Atlantic Current turns southward, flows along the "bulge" of Africa as the Canaries Current, then turns westward as the North Equatorial Current. This current crosses the ocean; part of its water reaches the Gulf of Mexico. South of the North Equatorial Current, running in the opposite direction, is the Equatorial Countercurrent.

South Atlantic Ocean:
In the South Atlantic, the cold Benguela Current flows northward up to the coast of Africa, turns west near the Equator, and flows westward as the warm South Equatorial Current. Near the South American coast, part of the current swings southward to become the Brazil Current, which runs down the coast of South America to about 40° South latitude. Here, it meets the cold Falkland Current. Flowing eastward across the South Atlantic in a broad belt around 50° S. is the West Wind Drift.