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Ocean Currents


    1.    Describe the relationship between wind and ocean currents.

    2.    Describe the patterns of different types  of currents.

    3.    Describe the flow of density currents.

    4.    Identify factors that affect the density of ocean water.

Key Terms:

    ocean current    surface current    cold-core ring    warm-core ring    countercurrent    density current    upwelling


Notes: (24-1 & 24-2)

Ocean currents are wide paths of water flowing over long distances in the ocean.  They are powered by the wind and affected by the Coriolis Effect.  The ocean currents can be broken down into surface and underwater currents.

Surface currents are defined as currents from the surface to 1000 meters in depth.  

turn clockwise in the northern hemisphere due to the Coriolis Effect
forms rings in the different oceans that are split into warm & cold currents
warm currents flow up on the west side from the equator
gulf stream (Atlantic), Kuroshio (Pacific)
cold currents flow down the east side from the polar regions
canary (Atlantic), California (Pacific)


Countercurrents are bands of water moving in the opposite direction as the prevailing current.  

can be surface or deep
serve to return water to an area as the Coriolis effect and prevailing winds pile the water up toward the west in the northern hemisphere.


Deep ocean currents known as density currents are different from surface currents in that the driving force is gravity and not the winds.  Density currents are global (not separated by hemispheres).  

flow vertically as well as horizontally and travel very slowly
are affected by the salinity (salt content) of the water
the greater the salinity the greater the density
evaporation removes water and increases salinity 
freezing at the poles consolidates fresh water and leaves behind cold condensed water with high salinity - densest water
provide the oxygen necessary for deep sea life

(2. The "Conveyor Belt")

Surface currents can travel from 500 - 2000 years before surfacing in a process knowi as upwelling.  

occurs primarily on the west coasts of continents as winds move surface water away from the coast


Last modified: February 10, 2004