1. Oceans and Ocean Movements

2. Cool Facts 71% of all water on Earth is in our oceans.
Average depth of the oceans is 2.65 miles deep!
Deepest point in the ocean is about 7 miles deep!
Pressure increases as you go down in the ocean.
Until 2000, there were only 4 oceans.

3. Oceanography The study of Earth’s oceans
Did not begin to study until 1800’s with the Challenger
Challenger: first research ship
Investigated ocean currents, temperature, and chemical composition of the ocean

4. Advanced Technology SONAR: SOund NAvigation and Ranging
Submarines to investigate deep ocean trenches

5. Scientists use SONAR to map seafloor and NOW can use it to understand aquatic life!

6. Origin of Oceans
Earth’s water may have originated from Comets or through volcanism.
Comets: carried water, collided with Earth, then released the water
Volcanoes: during eruptions, water vapor and carbon dioxide released, condensed, and formed Earth’s early atmosphere

7. The Major Oceans (5)
Pacific
Atlantic
Indian
Southern
Arctic

8. Pacific
Largest
Contains deepest point on earth! (7 miles deep-Marianas Trench)
Covers ~35% of the Earth
Between Asia and NA/SA

9. Atlantic Next to NC! Deepest Point: Puerto Rico Trench Second largest
Covers ~21% of Earth

10. Indian Deepest Point: Java Trench
Near India-Africa on East and Asia on North
Covers ~15% of Earth

11. Southern Ocean established in year 2000! Newest ocean
Surrounds Antarctica
Covers the South Pole

12. Arctic Smallest ocean Deepest Point: Arctic Basin Covers North Pole
Often completely frozen during the winter

13. Sea Level Level of the oceans’ surfaces
Can change in response to the melting of ice during warm periods and/or expanding of glaciers during ice ages
Average sea level is rising at a rate of 1 to 2 millimeters per year  because glaciers are melting (indicates a warm period)

14. Composition of Ocean Water
96.5% pure water and 3.5% salts
Salinity: total amount of solid material (salts) dissolved in water
Salinity measured in parts per thousand (ppt).

15. Where does the salt come from?
Salt = NaCl = the salt you put on food!
Comes from erosion
Salinity can decrease by precipitation, runoff from land, melting of ice (all adding more freshwater)
Salinity can be increased by evaporation (only the water evaporates, not the salt) and by sea water freezing (only the water freezes, not the salt)

16. Why are our oceans salty?
Salinity affects density!
We need changes in density so we can have ocean currents (we will study this in a few days)
So what makes our water MORE dense? Less salt or More salt?

17. Profile of an Ocean
Ocean water is warmer at the surface because of the sun.
Temperature decreases with depth.
Thermocline: zone in ocean where there is rapid temperature change.

18. Density and how it relates to temperature.
Colder water is more dense…means it will be below warm water.
Because of this, there are 3 zones:
Surface zone: at top
Transition zone: in middle (includes thermocline)
Deep zone: at bottom. Sunlight never reaches this section. 80% of ocean water found here.

19. Surface Zone
Transition Zone
Deep Zone

20. Ocean Movements
Ocean water moves in 3 ways:
Waves
Currents
Tides

21. Waves The movement that carries energy through the water
Most waves are caused by wind moving over the water’s surface.

22. Anatomy of a Wave Crest: top of the wave Trough: bottom of the wave
Wave height: vertical distance between the trough and the crest
Wave length: horizontal distance between two crests or troughs.

23. Ocean Currents
Masses of ocean water that flow from one place to another

24. 2 types of currents
Density currents: vertical currents that result from different densities of water. Denser water sinks.
Surface currents: movements of water that flow horizontally in the upper part of the oceans surface-usually because of wind.

25. What ultimately fuels the currents?
THE SUN
Warms waters on surface-makes them less dense
Causes evaporation-makes water more salty and therefore more dense

26. Tides Periodic rise and fall of sea level
Caused by gravitational attraction between the earth and moon.
Side of the earth facing the moon and opposite the moon experience tides.
Usually 2 high and 2 low tides a day

27. Spring Tide
When the earth, moon, and sun are all lined up. This creates higher, high tides and lower, low tides. Occurs at full and new moons.

28. Neap Tide
During a first or third quarter moon, when the moon is at a right angle to the earth. Results in lower, high tides and higher, low tides.

29. Tidal range
Difference in height between successive high and low tides.
If high tide is 4 meters and low tide is 1 meter, what is the tidal range?

30. Tidal Patterns
Diurnal tides: a single high tide and a single low tide each day
Semidiurnal tides: two high tides and two low tides each day
Mixed tides: two high and two low a day but the the heights are different between the two high and two low