Pre-Activity Questions

Name___________________________________________________________________Period_______

Ocean currents

Ocean currents are important to understanding how life is distributed in the oceans. There are two types of ocean currents, thermohaline (or density) currents and surface currents. You will look at a number of pictures to help you understand what causes these currents and how they affect life.

Pre-activity questions

1. Think back to the video that we watched about Antarctica. What happens to the ocean water that freezes?

2. Where are two ways that plants and animals return nutrients (like nitrogen) to the soil?

3. In the ocean, where would these nutrients end up?

4. In the ocean, where would the most sunlight be found?

Thermohaline (density currents)

5. Look at the picture of the thermohaline ocean currents. What happens to the water in the Atlantic Ocean in between North America and Europe?

6. What causes these currents to occur?

7. Look at the current just south of Alaska. What is happening to the current there?

8. What would these currents bring to the surface of the ocean just below Alaska (hint: think of the nitrogen cycle)?

Upwelling

9. When nutrients are brought to the ocean surface, this allows phytoplankton to grow, which provides food for many different sea animals. This is called upwelling. According to the picture of upwelling, where would most life in the oceans be found?

10. Why would upwelling occur at these locations?

Global wind pattern and surface ocean currents

11. Look at the global wind pattern. Which way does the wind move near

a. the equator?

b. between 30 and 60 degrees latitude?

12. Look at the surface ocean currents. Which way do the ocean currents move near

a. The equator?

b. Between 30 and 60 degrees latitude?

13. According to the information in #8 and #9, what causes the surface ocean currents?

14. According to the surface ocean currents map, how would the temperature of the ocean off the coast of California compare to the East coast?

The picture above shows thermohaline ocean currents. These are also known as density currents.

The picture above shows areas of upwelling. These are places where nutrients from the ocean floor are brought to the surface by ocean currents. These nutrients allow phytoplankton to grow rapidly, providing the basis for the ocean food chain. These nutrients come from dead plants and animals and their waste that sinks to the ocean floor. Phytoplankton produces about half of the oxygen that we breathe. The remains of phytoplankton from millions of years ago have turned into crude oil, which provide much of the basis of our modern society.

The picture above shows the global wind pattern. This wind pattern is caused by unequal heating of Earth’s surface and the coriolis effect. The Earth is unevenly heated because of the change in the angle of sunlight from the equator to the poles. The coriolis effect is caused by the Earth’s rotation.

The picture above shows surface ocean currents. Look for the pattern between the ocean currents and the wind currents.