Oceans 11
Investigating Thermal Layers
10/5/2014
Investigating the Vertical
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Thermal Structure
Name: ____________
Section: ___________
Introduction
Water temperatures below the surface are measured using a bathythermographs, an electric sensor
that keeps track of the various temperatures at prearranged depths from the surface to the bottom.
Warm water tends to be less dense and “floats” on top of the ocean (from lab #1), where it is
heated by the sun. Cold water is more dense and sinks to the ocean floor. A third region in which
the temperature changes most drastically within a narrow range of depth called a thermocline. In
this investigation we will consider the structure of the 3-layer temperature profile from the surface
(0 meters) down to 2 000 meters, and compare high latitudes, middle latitudes and tropical waters.
But remember, density causes the water layers to be arranged the way they are.
Procedure:
1. Use a single sheet of graph paper to plot the following four sets of data on the same graph. Let
the x-axis represent temperature from 0° to 30° and let the y-axis represent depth in meters , Use a
ruler and take your time doing this activity as messy, illegible graphs will have to be redone
to be accepted. Use different colours to represent each data set.
2. On your graph, lightly shade the epipelagic zone (0 to 200m) [LIGHT BLUE] and
mesopelagic zone (200 - 1000m) [Dark Blue] and bathypelagic zone [grey or lightly shaded
black]
(low lat = low latitudes, tropical ; mid lat = middle latitudes; high lat = high latitudes, polar)
Depth, m
Low lat
Mid lat,
summer
Mid lat,
winter
High lat
0
28
18
10.2
7.5
125
13
10.2
10.2
0
250
9
10.1
10.1
3.75
375
7.5
10
10
3.5
500
6
8.7
8.7
3.25
625
5.5
7.5
7.5
3
750
5
6.5
6.5
2.75
875
4.5
5.8
5.8
2.5
1000
4.4
5.1
5.1
2.5
1125
4.1
5
5
2.4
1250
3.8
3.8
3.8
2.3
1375
3.2
3.2
3.2
2.1
1500
3.1
3.1
3.1
2
1625
3
3
3
1.8
1750
2.8
2.8
2.8
1.5
1875
2.6
2.6
2.6
1.3
2000
2.5
2.5
2.5
1.25
Oceans 11
Investigating Thermal Layers
10/5/2014
Analysis
1. Describe the general shape of the temperature depth curve:
(a) at low latitudes
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(b) at mid latitudes in the summer
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(c) at mid latitudes in winter
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(d) at high latitudes
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2. Which two locations (latitudes) would require a dry suit for extreme cold conditions?
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3. Do any of the lines show an increase in temperature with increasing depth? Suggest a reason as
to why or why not this might the case?
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4. Which region shows the most rapid temperature decline and which shows the slowest
temperature decline?
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Oceans 11
Investigating Thermal Layers
10/5/2014
5. Using this graph extrapolate what the temperature might be in each region at 3000m deep
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6. Write a short summary explaining what happens to the water temperature profile from the surface to 125m deep at each latitude
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7. How does the epipelagic zone’s temperature profile differ from the mesopelagic and
bathypelagic zone temperature profiles?
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Oceans 11
Investigating Thermal Layers
10/5/2014
8. Swimmers rarely find these thermal layers at a beach. Suggest a reason why we might not
experience massive layers of hot and cold water at the beach.
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9. Math Connection [8 pts]
Determine the rate at which the temperature is changing for each latitude in °C per 100m
(a) at low latitudes between 0m and 200m
(b) at mid latitudes in summer between 0m and 200m
(c) at mid latitudes in winter between 0m and 200m
(d) at high latitudes between 0m and 200m
Hint:
rate of temp change, C/100m
(temp at 200m) - (temp at 0m)
1000
(e) at low latitudes between 1000m and 1700m
(f) at mid latitudes (winter) between 1000m and 1700m
(g) at mid latitudes (Summer) between 1000m and 1700m
(h) at high latitudes between 1000m and 1700m
100
Depth,m
0
2
4
6
8
10
12
16
Temperature,°C
14
18
20
22
24
26
28
30
Investigating Thermal Layers
-2200
-2000
-1800
-1600
-1400
-1200
-1000
-800
-600
-400
-200
0
Oceans 11
10/5/2014