Earth Science

Water on Earth

Surface Ocean Currents

Study Tip
Review the guide “Earth as a Planet” to understand the Coriolis Effect.

Surface Currents

  • Surface currents can flow for thousands of kilometers and can reach depths of hundreds of meters
  • Do not depend on weather
Study Tip
Review the guide “Earth as a Planet” to understand the Coriolis Effect.
  • Remain unchanged even in large storms because they depend on factors that do not change
  • Surface currents are created by 3 things:
  • Global wind patterns
  • Rotation of the Earth
  • Shape of the ocean basins
  • Surface currents distribute heat around the planet and influence climate around the globe
  • Global winds blow in the same directions all the time and are related to the unequal heating of Earth by the Sun and the rotation of the Earth
  • Coriolis effect: more solar radiation strikes the equator than the polar regions
surface ocean currents
The major surface ocean currents.
  • Water in the surface currents is pushed in the direction of the major wind belts:
  • Trade winds: east to west between the equator and 30º N and 30º S
  • Westerlies: west to east in the middle latitudes
  • Polar easterlies: east to west between 50º and 60º north and south of the equator and the north and south pole
  • When a surface current collides with land, the current must change direction
  • Surface ocean currents create loops called gyres
  • Local surface currents are also found along shorelines
  • Longshore currents
  • Rip currents: potentially dangerous currents that carry large amounts of water offshore quickly
surface ocean currents
Longshore currents move water and sediment parallel to the shore in the direction of the prevailing local winds.
Concept Check
  • Describe the motion of a water particle that is stuck in a gyre in the North Pacific.
  • What should you do if you get stuck in a rip current?
  • What would happen if a major surface current did not run into a continent? Note that this is what happens with the Antarctic Circumpolar Current.