Formation and Distribution of Currents

  • Approximately 71% of the earth’s surface is covered by oceans, which are dynamic in nature. Ocean water moves horizontally and vertically. Its movement is influenced by temperature, salinity, density and the external forces like Sun, Moon and winds.
  • The horizontal motions of oceans are waves and ocean current. The vertical movement of ocean is tides.
  • Ocean currents are the continuous movement of water from one part of the ocean to another, in some defined direction.
  • Ocean currents can be classified on the basis of depth, i.e., surface and deep water currents, and temperature i.e., warm and cold currents.
  • Surface currents constitute ten percent of all the water in the ocean. Deep water currents make up the other 90 percent of the ocean water.
  • Warm currents bring warm water into cold areas. These currents flow from the Equator to the higher latitudes.
  • Cold currents bring cold water into warm areas. These currents flow from the higher latitudes to lower latitudes.
  • The causes of ocean currents are Earth’s rotation, wind system, temperature, salinity, configuration of coast, and bottom relief. Ocean water gets deflected due to the Coriolis force caused due to the rotation of Earth. Ocean water moves in the direction of prevailing winds due to the friction.
  • Water in the ocean near the Equatorial region is heated more than that near the poles. This unequal heating sets up convectional currents in the ocean.
  • Salinity affects the water density that causes currents.
  • Shape of the coast of continents obstructs the flow of current and diverts its movement.
  • Submarine relief usually deflects the ocean currents.
  • Each ocean has its own system of ocean currents.
  • Major warm ocean currents of Atlantic Ocean are Gulf Stream, Florida Current, North Equatorial Current, Norwegian Current and North Atlantic Drift.
  • Minor warm currents of Atlantic Ocean are Brazil Current and Florida Current.
  • Major Cold Currents of Atlantic Ocean are East Greenland Current, Labrador Current, Canary Current, Benguela Current and Falkland Current.
  • Major warm ocean currents of Pacific Ocean are North Equatorial Current, South Equatorial Current, Central Equatorial Current, Eastern Australian Current, and Kuroshio Current or Japan Current.
  • Major Cold Currents of Pacific Ocean are Californian Current, Peru (Humboldt) Current, Oyashio Current or Kurile current, and West Wind Drift.
  • Major Ocean Currents of Indian Ocean are Southern Indian Ocean current, South equatorial Current, Agulhas Current, Mozambique current, cold West Wind Drift, South-West Monsoon current and North-East Monsoon current.
  • These ocean currents affect climate (rainfall and fog), marine organisms and also economy.

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  • Q1

    Mention any four major ocean currents in Pacific Ocean?


    i) Californian current ii) Humboldt current iii) East Australian current iv) Kuroshio current

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  • Q2

    Classify the ocean current on the basis of temperature with an example.


    Cold current – Example: California Current
    Hot current – Example: Alaska Current

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  • Q3

    Mention any two cold ocean currents flows in the northern hemisphere.


    Labrador current and Oyashio current

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  • Q4

    What are the different kinds of movement of ocean water?


    Ocean movements are mainly in the form of waves, tides and the ocean currents.

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  • Q5

    Name the deepest trench in the world and where is it located?


    Mariana Trench is the deepest trench in the word having 10.800 meters depth below sea level. It is located in the North Pacific Ocean.

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