1. Physical Oceanography
Chap. 15
The Oceans
Sea Water
Ocean Movements

2. The Oceans – 15.1 Objectives
identify methods used by scientists to study Earth’s oceans
discuss the origin and composition of the oceans.
describe the distribution of oceans and major seas

3. Introduction Uses Studying H.M.S. Challenger
travel
fishing/food
recreation
Studying
H.M.S. Challenger
Meteor
TOPEX-Poseidon
Used sonar to map undersea topography
NASA satellite that measures ocean data

4. TOPEX/Poseidon tracks ocean tides
measures sea levels (to 5 cm accuracy)
monitors climates by measuring ocean temperatures.

5. Ocean origins Oceans are as old as Earth’s rocks
Lava flows have been dated at 4.6 b.y.
These formed rocks by cooling quickly (in water)

6. Ocean origins Oceans are as old as Earth’s rocks Source of water
Comets (dirty snow balls)
Water was trapped in Earth when it formed. Volcanoes released this into the atmosphere.

7. The Hydrosphere Type Percentage Volume Used in Model Total 100 %
2000 mL
Salt Water (oceans)
97.2%
1941 mL
Fresh Water
2.8%
56 mL
Ice
2.3%
46 mL
Underground
0.4%
8 mL
Surface
~ 0.05%
1 mL
Soil & Air
~ 0.01%
0.2 mL

8. Earth’s Water Location Amount of frozen water has varied
During ice ages as much as 10% of hydrosphere was frozen.
Sea level varied by hundreds of meters.
Due to melting of glaciers and tectonic forces altering sea floor.

9. Earth’s Water Most of Earth’s surface is covered by water (71%)
The hemisphere contains higher percentage of water.

10. Earth’s Water Most of Earth’s surface is covered by water (71%)
The southern hemisphere contains higher percentage of water.
All oceans are connected.
Pacific, Atlantic, and Indian oceans are main oceans.
Seas are partly or mostly surrounded by land.
Sea ice forms in the Arctic and Antarctic seas.

11. Seawater
Objectives
compare & contrast physical and chemical properties of seawater
explain ocean layering
describe the formation of deep-water masses

12. Chemical Properties Salinity
Sea water is about 35 parts per thousand (ppt) salts
Salts include Na+, Cl- , SO42-, Mg2+, Ca2+, K+, HCO3-, and others

13. Chemical Properties Salinity
The salinity varies and is lower where there is . . .
a lot of precipitation
an estuary/river delta
melting of glaciers

14. Chemical Properties Salinity Source of sea salt
the atmosphere (Cl- and SO42-)
weathering rocks (Na+, K+, Ca2+ from feldspar)
5. Removing sea salt
deposited when water evaporates

15. Chemical Properties Salinity Source of sea salt Removing sea salt
deposited when water evaporates
carried via sea spray
marine organisms use it in building shells, bones, and teeth

16. Physical Properties Density is greater than 1.00 g/cm3
Density of fresh water is 1.00 g/cm3
Freezing point is less than 0ºC
Light absorption

17. Physical Properties Light absorption Water absorbs light
Some colors penetrate further than others

18. Physical Properties Layers The deeper you go the cooler the temp.
Temperature profiles show water depth/temperature relationship
The thermocline is a layer in which the temperature decreases linearly with depth
There is no thermocline for polar seas

19. Physical Properties
Water masses
Cold water comes from polar seas

20. Physical Properties Water masses Cold water comes from polar seas
Surface water sinks as salinity increases due to sea ice formation

21. Physical Properties Water masses Cold water comes from polar seas
Surface water sinks as salinity increases due to sea ice formation
Deep currents carry water to the equator

22. Ocean Movements – 15.3 Objectives
describe the physical properties of waves
explain how tides form
compare and contrast various ocean currents

23. Waves
Periodic movement that carries energy from one place to another.

24. Waves Wave characteristics Crest Trough Wavelength
Wave Height
The peak of a wave
Lowest part of a wave
Distance between successive wave crests (or troughs)
Depends on wind speed, wind duration, and fetch.

25. Waves Wave characteristics Breakers Waves slow down
Waves become unstable
Collapsing waves
More friction with ocean bottom causes waves to slow.
The tops of the waves collapse forward because the bottoms are being slowed

26. Waves
Tides
Periodic rise and fall of sea level.

27. Waves Tides High tide Low tide
Highest level to which water rises (a bulge of water)
High tide
Low tide
Lowest level water rises (caused by lack of water)

28. Waves
Tides
Types of daily cycles
Semidiurnal
Mixed
Diurnal

29. Waves Tides Cause of tides Gravity from the moon pulls on earth/oceans
Centrifugal motion moves the water away from Earth

30. Waves Tides Cause of tides
During spring tide (unrelated to the season) high tides are highest
During neap tide high tides are lower and low tides are higher than normal
The sun influences tides to a smaller degree
This is because of the greater distance between Earth and the sun (compared to Earth and the moon)

31. Ocean Currents Density currents Surface currents
Move bottom water according to temperature and salinity differences
Driven by surface wind.
Follow global wind patterns
Currents from the poles bring colder water, while currents from equator bring warmer water
Gyres develop due to landmasses interacting with current flow
Circular surface ocean currents

32. Major Ocean Currents

33. Ocean Currents Upwelling brings nutrient-rich water.
Movement of cold water upward as surface water is blown by offshore winds

34. The End