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
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
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.