Oceans

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Oceans

• Surface Currents

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What are surface currents?

• Surface currents are horizontal, streamline
  movements of water that occur at or near the
  surface of the ocean.
• Surface currents can reach depths of several
  hundred meters and lengths of several thousand
  kilometers, and can travel across oceans.

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Surface current formation

• As wind blows across the ocean, it drags water
  along with it creating strong currents. Because
  the winds reach is limited, these surface
  currents only run about 200 meters (656 feet)
  deep.
• Short lived winds create temporary surface
  currents. Constant winds create more permanent
  currents that flow strongly on a fixed course.

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What controls surface currents?

• 1. Global Winds
• 2. Coriolis Effect
• 3. Continental Deflection

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Wind Creation

• The sun heats the Earths atmosphere unevenly,
  creating very warm, high-pressure areas around
  the equator, and cool, low pressure areas toward
  the poles. As the warm air moves to low pressure
  areas, wind is created. Uninterrupted, wind
  patterns would run in straight lines from pole to
  pole.

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What factors contribute to surface current
formation?

• 1. Global Winds- winds that blow across the
  Earths surface create surface currents. They act
  as a heat transfer system. Global winds are due
  to the unequal heating of earths surface.

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• 2. The Coriolis Effect the apparent curving
  of moving objects from a straight path due to the
  Earths rotation.

Because of the Earths rotation wind is forced
right or left, depending on the hemisphere it is
in.
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• 3. Continental Deflection when surface
  currents meet a continent it deflects the
  movement of the current.

The Gulf Stream deflects off the coast of North
America and flows across the ocean to the British
Isles. As a result, the British Isles have a
milder climate than Canada.
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Why are some surface currents cold and others are
warm?
Warm water surface currents originate in the
tropics and flow north and south from the
equator. As the water moves farther north it
cools and sinks. The colder water on the surface
then moves north or south from the poles and
warms as it gets closer to the tropics.
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Map of Surface Currents
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California current along the coast of California
is a cold water current, causing cooler water
temperatures.
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The Gulf Stream is a warm water current that
flows along the gulf and Florida, causing warmer
water temperatures.
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Gulf Stream current.