1. Earth Science
Coach Williams
Room 310B

2. Chapter 15
Physical Oceanography

3. Section 15.1: The Oceans 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

4. Oceanography
The study of Earth’s oceans

5. Modern Oceanography Sonar: SOund NAvigation and Ranging”
Mapping ocean floors
Side-scan sonar: angles
Satellites: monitor water temp/ waves

6. Origins of Oceans Earth: 4.6 billion years old
Ocean sedimentary rock
Igneous rock- lava chilled quickly = water
Where did ocean water come from?
Meteorites colliding release water
0.05% of meteorites are water
Volcanism: water vapor

7. Distribution of Earth’s Water
Oceans: 97% of Earth’s water
Freshwater/glaciers: 3%
Sea Level: level of the ocean
Ice makes sea levels vary
Sea floor rising/falling
71% of planet is covered by oceans
Major Oceans: Pacific, Atlantic, Indian
Other oceans: Arctic & Antarctic
Seas: smaller than oceans and usually land- locked

8. Oceans

9. Section 15.2: Seawater Objectives:
Compare/contrast the physical and chemical properties of seawater
Explain ocean layering
Describe the formation of deep-water masses

10. Chemical Properties of Seawater
96.5% water & 3.5% dissolved salt (NaCl)
Salt is metal & group17 on periodic table
Salinity: amount of dissolved salt
Average: 35ppt (parts per thousand)
Lower: polar regions, river/ocean, high precipitation
Higher: low precipitation/high evaporation
Salt: Volcanism, weathering/rivers
Dissolved gasses: O, N, CO2
Salt balance: precipitate, ocean spray, animals

11. Physical Properties of Seawater
Density: more dense than pure water >1
Salinity, temperature
Freezing point lowered (-2°C)
Darkness: ocean water absorbs light (100m)

12. Ocean Layering Range of surface temp.: -2°C through 30°C (Avg=15°C)
Depth & temp.: deeper = colder
Temp. Profile: plots temp. with depth
3 Layers (based on temp./density)
Surface layer
Thermocline: rapidly decreasing temp.
Bottom layer

13. Ocean Layering

14. Water Masses Warm tropic water rises Polar waters sink 3 Ocean Masses:
Antarctic Bottom Water
North Atlantic Deep Water
Antarctic Intermediate Water

15. Water Masses

16. Section 15.3: Ocean Movements
Objectives:
Describe the physical properties of waves
Explain how tides form
Compare/contrast various ocean currents

17. Waves Wave: movement that carries energy Caused by wind
Water moves up and down; energy moves forward

18. Wave Characteristics Crest: tallest part Trough: lowest part
Wavelength: distance between wave
Wave base: how deep water is disturbed
½ of wavelength
Speed of wave affected by wavelength
Speed = wavelength x frequency
Wave height: distance from crest to trough
Wind speed
Wind duration
Fetch: how much open water

19. Wave Characteristics

20. Breaking Waves Breakers: collapsing waves
Friction with bottom slows water down
Faster waves catch slower moving water
Faster water at top
Shapes shoreline

21. Tides Periodic rise/fall of sea level
High Tide: highest level
Low Tide: lowest level
Tidal range: difference between two levels

22. Causes of Tides Gravitational pull: Earth, Moon, Sun
Gravity depends on mass and distance
Sun: larger mass (Solar Tides)
Moon: closer (Lunar Tides)
Spring tides: Sun/Moon/Earth aligned
Tides are higher/lower than normal

23. Causes of Tides

24. Ocean Currents Density currents: Surface currents:
Caused by density differences (salinity/temp.)
Slow moving
Surface currents:
Wind driven currents
Top 100m
Faster
Predictable patterns
Gyres: circular current systems

25. Ocean Currents

26. Gyres

27. Upwelling
Movement of water up and down
Brings nutrients from deep