Great circles of water
Gyres in the oceans.
A whirl in the sea
Moving ocean water does not go in a straight line forever. The Earth turns, and land gets in the way.
What shape might the paths of moving ocean water take?
What this lesson covers
The idea
The Earth's rotation deflects moving ocean water into large circular gyres, clockwise in the Northern Hemisphere and counter clockwise in the Southern Hemisphere, while continents block and redirect currents.
A whirl in the sea
Moving ocean water does not go in a straight line forever. The Earth turns, and land gets in the way.
What shape might the paths of moving ocean water take?
- Large circles
- Straight lines forever
- Zigzags
Gyres and coasts
Open every tab.
Circles caused by rotation
The turning Earth bends moving water into huge circles. The direction of the circle depends on the hemisphere. Land stands in the path of moving water and turns it aside.
The Earth's rotation deflects moving ocean water into large circular gyres, clockwise in the Northern Hemisphere and counter clockwise in the Southern Hemisphere, while continents block and redirect currents.
Notes
The Earth's rotation deflects moving ocean water into gyres: clockwise in the Northern Hemisphere, counter clockwise in the Southern Hemisphere. Continents block and redirect currents.
Check yourself
What are gyres?
In which direction do gyres rotate in the Northern Hemisphere?
In which direction do gyres rotate in the Southern Hemisphere?
What forms the circular gyres?
- Strong winds above the ocean. Gyres are circular patterns of moving ocean water, not winds.
- Large circular patterns of moving ocean water — correct. Yes!
- Layers of salty water. Gyres are large circular patterns of moving water.
- Counter clockwise. Gyres rotate counter clockwise in the Southern Hemisphere.
- They do not rotate. The Earth's rotation deflects moving water into circular gyres.
- Clockwise — correct. Yes!
- Counter clockwise — correct. Yes!
- Clockwise. Gyres rotate clockwise in the Northern Hemisphere.
- Straight towards the pole. The Earth's rotation deflects moving water into circular patterns, not straight lines.
- Continents blocking and redirecting currents alone. Continents modify the paths further, but the circular gyres form because the Earth's rotation deflects the moving water.
- The Earth's rotation deflecting moving water masses — correct. Yes!
- Water with higher salinity sinking. Salinity differences move water up and down. The Earth's rotation deflects the moving water into gyres.