Name: ___________________
Period: ___________________
Variations in Ocean Water
Use Figure 3 and the information on page 424 to answer the following.
1. What information does the graph show? (2 different topics)
2. At which latitude is sea surface salinity the lowest?
3. Where is your answer from #2 found on the globe?
4. What time of year do you think these salinity readings were taken? Explain.
5. In what ways can temperature affect salinity?
Use Figure 4 and the information on page 425 to answer the following.
6. What information do the two graphs show?
7. What is the thermocline?
8. What is the temperature range with the thermocline at low latitudes?
(Hint: watch the depth to stay within the thermocline)
9. Why is the thermocline absent at high latitudes?
Use Figure 5 and the information on page 426 to answer the following.
10. What information do the two graphs show?
11. What is the pycnocline?
12. Compare Figure 4 with Figure 5. How are the temperature and density of the
ocean water in latitudes related?
13. Do you think there is ever a time that there is a pycnocline present at high
latitudes?
Use Figure 6 and the information on page 427 to answer the following.
14. Describe the Surface Zone or the Mixed Zone.
15. Describe the Transition Zone.
16. Describe the Deep Zone.
17. Explain why the three-layered water structure does not exist in high latitudes.
Variations in Ocean Water - KEY
Use Figure 3 and the information on page 424 to answer the following.
18. What information does the graph show? (2 different topics)
a. Ocean surface temperature – red line
b. Surface salinity – blue line
19. At which latitude is sea surface salinity the lowest?
a. 60°N
20. Where is your answer from #2 found on the globe?
a. Near the Arctic circle
21. What time of year do you think these salinity readings were taken? Explain.
a. Spring or summer – the melting of the ice in the Arctic has caused the ice
to melt, thus decreasing salinity.
22. In what ways can temperature affect salinity?
a. Above-freezing temperatures allow the polar ice to melt, adding fresh
water to the ocean surface and decreasing salinity. Ice formation in
below-freezing temperatures removes fresh water and will cause an
increase in salinity values
Use Figure 4 and the information on page 425 to answer the following.
23. What information do the two graphs show?
a. Depict variations in ocean water temperature with depth at the high and
low latitude regions.
24. What is the thermocline?
a. Layer of ocean water between 300-1000 meters where there is a rapid
change in temperature with depth.
25. What is the temperature range with the thermocline at low latitudes?
(Hint: watch the depth to stay within the thermocline)
a. 24°C – 4°C
26. Why is the thermocline absent at high latitudes?
a. Surface temperatures are much cooler at high latitudes. Deeper in the
ocean, the temperature of the water is similar to the surface. There is no
rapid change of water temperature. This is called isothermal, which
means same heat.
Use Figure 5 and the information on page 426 to answer the following.
27. What information do the two graphs show?
a. Depict variations in ocean water density with depth at the high and low
latitude regions.
28. What is the pycnocline?
a. The layer of the ocean water between 300-1000 meters where there is a
rapid change of density with depth.
29. Compare Figure 4 with Figure 5. How are the temperature and density of the
ocean water in latitudes related?
a. Temperature and density are inversely proportional. When the
temperature goes up, the density goes down. And when the temperature
goes down, the density goes up.
30. Do you think there is ever a time that there is a pycnocline present at high
latitudes?
a. Yes, during warmer seasons of the year, ice melt could add fresh water to
the upper layer of seawater. This would create a variation in density with
respect to water at greater depths.
Use Figure 6 and the information on page 427 to answer the following.
31. Describe the Surface Zone or the Mixed Zone.
a. Area of the surface created by the mixing of water by waves, currents and
tides. Uniform temperatures and accounts for 2%of ocean water
32. Describe the Transition Zone.
a. Below the sun-warmed zone, temperature falls abruptly with depth. There
some mixing between the warm water from the surface zone and the cold
water from the deep zone. The thermocline and the pycnocline are located
in the transition zone. This zone accounts for 18% of ocean water.
33. Describe the Deep Zone.
a. Sunlight never reaches this zone. The temperature is just a few degrees
above freezing and water density is remains constant and high. This zone
accounts for 80% of the ocean water.
34. Explain why the three-layered water structure does not exist in high latitudes.
a. There is no rapid change in temperature or density with depth. Good
vertical mixing can occur in high-latitude regions. Begins the density
currents – cold, high density water sinks and initiates the deep-ocean
currents.