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Oceanography
Chapter 37
5. Heating of Earth’s surface and atmosphere by
the sun drives convection within the
atmosphere and oceans, producing winds and
ocean currents. As a basis for understanding
this concept:
 a. Students know how differential heating of Earth results in circulation
patterns in the atmosphere and oceans that globally distribute the
heat.
 b. Students know the relationship between the rotation of Earth and
the circular motions of ocean currents and air in pressure centers.
 d. Students know properties of ocean water, such as temperature and
salinity, can be used to explain the layered structure of the oceans, the
generation of horizontal and vertical ocean currents, and the
geographic distribution of marine organisms.
Objectives
 Students will know the circulation
patterns of the oceans and how the heat
is distributed
 Students will know the properties of
ocean water, the layered structure of the
oceans, the generation of horizontal and
vertical ocean currents.
What is oceanography?
 The study of Earths oceans.
Chemical Composition of
water
 96.5% Fresh Water
 3.5% Dissolved Salts
 Most abundant salt
sodium chloride
 Other salts are
sulfates and
chlorides. These are
so dissolved called
ions.
 Dissolved gases

Oxygen, nitrogen
and carbon dioxide
 Dissolved Nutrients

Nitrates,
phosphates, and
silicates
 Both of these greatly
effect life in the
oceans.
Salinity
 Measurement of
amount of dissolved
salts in seawater.
 Measured grams of
salt per kilogram of
water
 Average 3.5 % or .35
ppt
 Salinity map showing
areas of high salinity in
green, medium salinity
in blue and low salinity
in purple.
Variations in Salinity
 Subtropical Regions


Rate of evaporation
exceed precipitation
Salinity is 37 ppt
 Equatorial Regions


Precipitation is abundant
Salinity is 34-35 ppt
 Polar regions

Salinity is 32-33 ppt
Physical Properties of
Seawater
 Seawater is denser than freshwater.
 Density varies depending on salinity and
temperature.
 Cold water is denser than warm water.
 Variations in salinity cause the freezing
point of seawater to be lower than fresh
water.
Ocean Layering
 Temperature Profile


Draw, label, explain and
color figure 37.15 on page
675
Plot changing water
temperature with depth
The three layered ocean with the upper mixed layer (yellow), main thermocline
Ocean Layers
 Surface layer

Warm and Sunlit layer
 Thermocline layer

rapid decreasing temperature
with depth.
 Bottom layer

Cold and dark near freezing
 Theromocline and Surface
layers are absent in polar seas
Important Phrases
 Repeat after me:
 Seawater is denser than
freshwater.
 Cold water is denser than
warm water.
Ocean currents
 Density current

Differences in salinity and
temperature cause this
current to move slowly
through deep ocean
waters
 Surface currents

Wind driven current that
effects the upper few
hundred meters of ocean
 Fast as 100 km per
day

See page 676 of book
Predictable Surface Currents
 Northern hemisphere

Trade winds blow east to west therefore tropical
ocean currents flow east to west
 Northern mid-latitudes

Prevailing Westerlies and resulting ocean current
travels west to east
 Northern Polar Regions

Polar Easterly move polar currents east to west
Gyres
 Continents deflect
ocean currents north
and south this
creates closed
circular systems
called gyres.
 Five main gyres

North Pacific, North
Atlantic, South
Pacific, South
Atlantic, and the
Indian Ocean
 When equatorial currents deflect off a
continent the warm ocean current moves
warm tropical waters toward the higher
colder latitudes in polar regions.
 The warm water cools is deflected by
landmasses and move back toward the
equator.
How does the Coriolis effect
gyres?
 Example- flushing toilet
 Northern hemisphere

Gyres move clockwise
 Southern hemisphere

Gyres move counter clock wise
Upwelling
 Ocean water moves vertically.
 Exist mainly on western coast of continents.
 Trade winds blow surface waters off shore and
that water is replaced with upwelling deep water.
 These waters are rich in nutrients, which
supports abundant populations of marine life.
Draw, label, and color figure
 An result of a upwelling is the richest
fishing grounds due to abundant marine
life.
 For example Peru and California
Review Sheet
 Define salinity.
 Explain how salinity varies in different areas and what effects




salinity.
What are the physical properties of seawater?
What is a temperature profile?
Describe the three different ocean layers.
Fill in the blanks;


Cold water is denser than _______water.
Seawater is denser than ____________.
 What are the two most important phrases to learn?





Differentiate between surface and density currents.
Explain how Trade winds effect surface currents and what direction
do each current travel.
Clarify what are gyres.
Why do currents just not travel east to west or west to east?
Explain an upwelling and what are the results from an upwelling.