Learning Target
—  I can define the 3 temperature zones
in the ocean and explain the
characteristics of each zone.
Guided Reading Review
Temperature Zones – pg.53
—  The temperature of ocean water decreases as
depth increases
—  This change is NOT gradual
—  Water in the ocean can be divided into three layers
by temperature
—  Water at the surface is much warmer than the
average water temperature
Ocean Temperature Zones
Surface Zone
•  Warm, mixed by waves—
aka “mixed zone”
•  Sunlight, plant growth
•  Temp depends on latitude
Thermocline
•  Temperature drops rapidly
with depth
Deep Zone
•  Uniformly cold
•  1-3 degrees C
•  Polar creep—ocean current
Cooler
Warmer
Changes in Surface
Temperature
Temperature of ocean water
_______________
decreases as depth
increases
Surface water temperature varies
with the
latitude
b. time of year
a.
•  Lower surface temperatures
are found in high-latitude
regions (away from the
_________
equator )
•  Higher temperatures found in
low latitude regions
_____
Global Thermostat
What is the most important function of the
oceans?
—  Absorb heat from the sun
—  Regulate the Earth’s climate
*
Why are waters at the equator
warmer than waters at
higher latitudes?
The equator receives
much more _______
direct light
and heat radiation from
the sun.
Away from the equator, the same
amount of light radiation is spread over
a much bigger area.
Thermocline Activity
Water temperature varies greatly based on both the depth of the
water and the location, closer to the poles or the equator. The
temperature of the water decreases as depth increases. However,
this temperature change does not happen gradually from the
ocean’s surface to its bottom. Water temperatures below the
surface are measured using a bathythermograph, an electronic
sensor that keeps track of the various temperatures at different
ocean depths. Warm water tends to be less dense and “floats”
on the top of the ocean, where it is heated by the sun. Cold
water is denser and sinks to the deep ocean floor. A third region
in which temperature changes most drastically within a narrow
range of depth is called the thermocline. In this activity we will
graph the temperature profile from the surface (0 meters) down
to 2,000 meters. Once we have the graphs we will compare the
temperatures from the poles, middle latitudes, and tropical
waters. Remember, that density causes the water layers to be
arranged the way they are.
Procedures
1.  Using the graph set up provided, plot the temperatures of the
following four locations.
2.  Using four different colored pencils you will make a line graph for
each latitude region.
3.  The graph has been set up for you with increasing temperature on
the x-axis with a scale of 1 °C and increasing depth on the y-axis
with a scale of 100 m.
4.  Create a key on your graph using the space provided for the four
temperature locations.
5.  Once you complete the four lines label each line with the region it
represents (low latitude, mid (summer), mid (winter), and high
latitude)
6.  When your graph is complete read page 41 (Temperature Zones and
Figure 5); page 42 (Surface Temperature Changes); and all of page
44 (A Global Thermostat). Then answer the analysis and conclusion
questions.
Homework
—  Complete thermocline graph (steps 1-4)
—  Study for quest on Monday
Closure
• What stuck with you this lesson?
• Place a star in the self-assessment box
that matches how you feel about ocean
temperatures.
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