Teacher Site Map
Earth Systems Science Core
Science Home Page
USOE

How Does Earth's Spinning Affect Wind And Ocean Patterns?

If Earth did not rotate on its axis, winds would blow from the north toward the south and from the south toward the north. A straight line, as drawn from the equator towards the North Pole or from the North Pole to the equator, as indicated in the example to the left, models this kind of wind direction.

 

 

Since the earth rotates on its axis from west to east, both the wind and ocean currents move from east to west. Thus the wind movement and ocean currents in the northern hemisphere go clockwise and counter clockwise in the southern hemisphere.

Notice the difference between the lines drawn when the globe did not move (shown with arrowheads) and the lines which were drawn as Earth rotated.

 

The Coriolis Effect also causes ocean surface currents to be deflected to the right of the winds. At the equator there is no Coriolis Effect, so there is no or very little deflection. At other latitudes each layer of water (depth) is set into motion by the Coriolis Effect. Each layer moves at different velocities and moves to the right until, if you were to look from above, a spiral shape of ocean currents would form. View a QuickTime video modeling the effect of the Coriolis Effect.

As seen in the diagram at the right, adding each of these directions together produces a net current of flow which is perpendicular to the wind within about the top 100 meters of ocean water. This phenomenon causes currents in the northern hemisphere to move in a clockwise direction and a counterclockwise direction in the southern hemisphere. If there were no continents or island land masses, each of the ocean currents would have either an easterly or westerly flow. However, landmasses interrupt the flow of ocean currents, creating closed circular current systems called gyres.  The five major gyres are the North Pacific Gyre, the South Pacific Gyre, the North Atlantic Gyre, the South Atlantic Gyre and the Indian Ocean Gyre. The parts of all gyres closest to the equator move toward the west as equatorial currents. As these gyres encounter landmasses, they are deflected toward the poles. They carry warm ocean water toward cooler regions, affecting not only ocean water but the air temperatures as well. These warm currents, such as the Gulf Stream and the Japanese Current, help moderate the weather, keeping air temperatures warmer. A prime example can be found along the western coasts of Great Britain. Warm Gulf Stream water from the Gulf of Mexico helps keep the climate more moderate. Compare the same latitude to that of central Canada.

In addition to surface currents, water also moves vertically as deeper water rises toward shallower depths. This is referred to as upwelling. Upwelling can occur during a La Niña event, where warmer surface waters and air temperatures are blown from the western coasts of South America toward Indonesia and Australia. Deeper water from below rises toward the surface, replacing the horizontally moving water. The upwelling water is cooler and more nutrient rich, causing a decrease in air temperatures near the surface.

Using the information above, label the five gyres on a world map. Also label the following currents: South equatorial current, the North Equatorial Current, the North Pacific Current, the California Current, the EAC, the South Equatorial Current, the Gulf Stream, the Canary Current, the Peru Current, the North Atlantic Current and the Alaska Current.

 
Review science lab safety rules here.

Get the plug-ins: Get Adobe Acrobat Reader and Get Quicktime Player. (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information:

  1. The title of the activity
  2. The URL (Internet address)
  3. Your name.

Remember that no pictures can be used that show student faces or student names on it. 

Teachers should view the Teacher Site Map to relate Sci-ber text and the USOE Earth Systems Science core.

 


Updated October 24, 2008 by: Glen Westbroek

Science Home Page | Curriculum Home Page | Earth Systems Science Core | USOE Home Page


Copyright Utah State Office of Education.