Rivers in the sea

The idea

Ocean currents are continuous movements of large masses of ocean water, set in motion mainly by planetary winds dragging surface water by friction; by carrying heat from the equator towards the poles they reduce temperature differences.

Moving ocean

Warm water from near the equator can end up at far northern coasts.

What do you think pushes huge masses of ocean water around?

• Winds dragging the surface
• Nothing at all
• Fish swimming

What moves the sea

Press Next step.

Heat on the move

Wind pushes the surface water along. The moving water carries heat from the hot equator towards the cold poles, so the difference in temperature between them becomes smaller. For example, the warm North Atlantic Drift flows towards the northwestern coast of Europe and keeps many ports ice-free during winter, even at high latitudes.

Ocean currents are continuous movements of large masses of ocean water, set in motion mainly by planetary winds dragging surface water by friction. By carrying heat from the equator towards the poles they reduce temperature differences.

Notes

Ocean currents are continuous movements of large masses of water, set going by winds dragging the surface. They carry heat from the equator towards the poles and reduce temperature differences.

Check yourself

What are ocean currents?

How do strong planetary winds start surface currents?

What do ocean currents do to the temperature differences across the planet?

What does the warm North Atlantic Drift do in winter?

• Waves that break on the beach. Ocean currents are continuous movements of large masses of ocean water, not breaking waves.
• Small ripples on a pond. Ocean currents involve large masses of ocean water.
• Continuous movements of large masses of ocean water — correct. Yes!
• They drag the surface water because of friction — correct. Yes!
• They heat the water at the bottom of the ocean. The chapter says the winds drag the surface water because of friction.
• They push water up from under the sea floor. The chapter says the winds drag the surface water because of friction.
• Increase them by carrying heat to the equator. Currents carry heat from the equator towards the poles, which reduces the differences.
• Reduce them by carrying heat from the equator towards the poles — correct. Yes!
• Leave them unchanged. By transporting heat from the equator towards the poles, currents reduce temperature differences.
• Brings ice to the ports of northwestern Europe. It is a warm current, so it keeps many ports ice-free during winter.
• Cools the equator. The chapter says it moderates the climate by keeping many ports ice-free, not by cooling the equator.
• Keeps many ports on the northwestern coast of Europe ice-free — correct. Yes!