Page 232 – 233 Currents
Science 8
1. Why does cooler water sink below warmer water?
Cooler water is more dense than warmer water.
2. Currents cause by temperature differences are called ____convection______currents.
3. What types of matter are carried in convection currents?
Nutrients and oxygen
4. What are two ways that oxygen gets dissolved in water?
Plants (like seaweed) produce it and waves mix it from the air
5. What is a turnover? (There is a mistake in the text – an overturn is something else!)
In spring and fall, the bottom and top layers of water in a lake trade places.
6. What problems do you think could happen if a large lake did not have turnovers?
No oxygen at the bottom of the lake (dead fishies) and no nutrients at the top for algae and plants
7. Flow currents (not described in the textbook) are strong currents in lakes caused by rivers flowing in or out. Why do you think flow currents are stronger than convection currents?
Convection currents depend on temperature, but flow currents only depend on how fast the rivers flow.
8. What is the common name for the movement of water due to the Sun and Moon’s gravity?
tides
9. How do you think strong winds would affect currents?
The current gets pushed in the direction of the wind
10. How do you think landforms on the ocean floor would affect currents?
The current gets diverted over or around the obstacle.
11. How do continents affect currents?
12. How does the text suggest you should imagine (picture) ocean currents?
Imagine currents as a river of water moving through the still ocean
13. What is a gyre?
It’s a circular movement of water in an ocean that occurs due to the combination of two or more currents.
14. What currents make up the North Atlantic Gyre?
They include the Gulf Stream, the North Atlantic Current , the Canary Current, and the Atlantic North Equatorial Current.
15. What do you think the word productivity means?
The amount of living material an ecosystem can produce.