1. Ocean composition

2. salinity
A measure of the amount of salts in water.

3. WAVES, CURRENTS AND TIDES
OCEAN MOTION
WAVES, CURRENTS AND TIDES

4. Currents What are currents? Causes - “Rivers” of circulating water
- Wind
- Rotating Earth
- Density Changes

5. Surface current – ocean current powered by the wind blowing across the surface of the water, moves only the upper few hundred meters of seawater, horizontally.

6. Surface Ocean Currents
Broad, slow drifts; never cross equator
Wind generated; circular gyres
Ocean current powered by the wind blowing across the surface of the water, moves only the upper few hundred meters of seawater, horizontally.

7. Upwelling – upward circulation of water in the ocean that brings deep, cold water to the top.

8. Density current
Circulation pattern in the ocean that forms when a mass of more dense seawater sinks beneath less dense seawater. (cold or salty water is more dense)

9. Importance Of Deep Currents
Upwelling
Brings deep water to surf.
Circulates nutrients up
Moves plankton & larvae

10. Coriolis effect
- N. Hemis – clockwise; Right
The Earth’s rotation causes moving air and water to turn left in the south and right in the northern hemisphere.
- S. Hemis – counterclockwise; Left

11. Gyre - A circular motion or vortex of water in the ocean
Gyre - A circular motion or vortex of water in the ocean. (traps plastic trash in the middle)

12. Wave – rhythmic movement that carries energy through matter or space

13. Waves look like hills and valleys; the crest is the highest point and the trough is the lowest point.

14. As a wave passes, energy moves forward; the water molecules remain in about the same place.

15. Wave height is the vertical distance between crest and trough.

16. Wavelength is the horizontal distance between crests or troughs of two adjacent waves.

17. A breaker is a collapsing wave.

18. The rise and fall in sea level, called a tide, is caused by a giant wave produced by the gravitational pull of the Sun and the Moon

19. Tides The rhythmic rise and fall of the ocean’s water
High tide = rising, incoming tide, flow
Low tide = receding, outgoing tide, ebb
Slack tide = vertical movement stops

20. Tides are very long, slow waves
They have a wave period of 12 hours 25 min
Tidal day is 24 hours 50 min
NJ has 2 high and 2 low tides daily

21. What Causes Tides? 1. Gravitational pull of sun & moon on Earth
Moon closer, therefore > effect
Like magnet, pulls water away from surface = TIDAL BULGE

22. 2. Centrifugal Forces
Bulge on opposite side because centr. force > pull of moon
Produced by motions of Earth, sun, & moon

23. Tsunami Waves

24. TSUNAMI “TIDAL WAVE” Caused by undersea quake or volcano
Wavelength = ~150 mi.
Wave height = 6” – 1’
Can NOT perceive in boat
Speed > 500 mph
Slows down to ~25 mph at shore; water builds up to ~65+ ft

25. Creation of a Tsunami

26. Distance bet. Moon & Earth
Perigee Tides
Moon closest to earth, very high tides (causes flooding)
Apogee Tides
Moon farthest away from earth, very low tides

27. Types of Tides Spring Tide
- Moon and sun are in direct line with one another
Results in
Tidal Range = vertical distance between high & low tides
2x’s/month

28. Neap Tide sun and moon are at right angles
Pulls cancel each other out – causes a weak pull
unusually low tidal range
2 x’s / month

29. High tide Low tide

30. Tidal Range
The difference in height between successive high and low tides.

31. Low tide – later, as the trough of the wave approaches, sea level appears to drop.

32. Ch. 19 The Ocean Floor

33. Basin A low area on Earth in which an ocean formed when the area filled with water from rain and moisture from volcanic eruptions.

34. Continental shelf – gradually sloping end of a continent that extends beneath the ocean.

35. Continental slope- feature of the ocean basin that dips steeply down from the shelf to the bottom.

36. Abyssal plain
Flat seafloor area below the surface of the water, formed by the deposition of sediments

37. Mid-ocean ridge
Area where new ocean floor is formed when lava erupts through cracks in the ocean floor.

38. Trench- Long, narrow steep-sided depression in the sea floor formed where one crustal plate is sliding underneath another one.