th
8
Grade Science
Test Review
Ch 2-3 Oceans & Currents

1. What two factors affect the ocean’s surface temperatures?
Two factors that affect the surface temperature of the oceans are latitude and time of the year.
2. Define salinity.
Salinity is a measure of the amount of dissolved salts in given amount of liquid.
3. What two factors increase the salinity of ocean water?
Evaporation and also if the water is slow moving it will have a higher salinity.
4. Explain how rivers cause the salinity of ocean water to increase.
Rivers help the salinity of the water to increase because the rivers are carrying sodium chloride and other minerals so they will run into the ocean.
5. Explain how rivers cause areas of low salinity in the ocean.
They have a low salinity because more fresh water from streams and rivers run into the ocean.
6. How does circulation of ocean waters affect salinity?
If the ocean is not moving it has a higher salinity than a place that has more circulation.
7. What are the most abundant elements in ocean water?
The two most abundant elements in the water are sodium and chlorine.
8. What is happening to the size of the Pacific ocean?
The Pacific Ocean is shrinking.
9. List 3 renewable resources from the ocean.
Three renewable resources from the ocean are fish, tides, and kelp.
10. How do surface currents affect the climates of coastal areas?
Warm-water currents make the coastal areas have a warmer climate and cold-water climates make coastal areas colder.
11. What causes surface currents?
Surface currents are caused by global winds, the Coriolis effects, and continental deflections.
12. What does the Coriolis effect do to surface currents?
The Coriolis effect makes the surface currents to curve across the Earth’s surface. In the south they move counterclockwise and in the north they move clockwise.
13. How does temperature affect the density of water?
Warmer water is less dense because the particles are spread farther so it takes up more volume. Colder water is more dense because the particles are close together.
14. What happens to water particles when water gets cold?
When water gets cold the particles slow down and come closer together.
15. How does salinity affect the density of water?
If you have a high salinity the water is denser because there is more salt packed in the water.
16. Where does the warm water at the equator move to?
The water moves away from the equator.
a. How does it get there?
It gets there through currents.
17. Compare the temperature and density of deep currents to surface currents.
Surface currents are warmer and are less dense while deep currents are colder and are more dense. 18. What is El Nino?
El Nino is a change in the water temperature in the Pacific Ocean that produces a warm water current. 19. What are some negative effects of El Nino?
Some negative effects are flash floods, drought, and mudslides.
20. What causes tides to occur on Earth?
The gravitational pull of the moon causes tides.
From Ch 1 (Freshwater) Test
21. Describe what happens to the motion of the particles when water evaporates.
When water goes from a liquid to a gas the particles speed up.
a. Is this change of state endothermic or exothermic?
Energy is