2. Why does the ocean move? The tides, waves, and currents cause motion in the ocean They are the result of interactions of many forces and factors Conditions in the Earth’s atmosphere The movement of our planet in space The Earth’s interactions with other bodies in our solar system

3. Tides

4. The tide is the daily rise and fall of the ocean as seen along the shore The highest elevation that the ocean reaches along the shore is called HIGH TIDE The lowest elevation that the ocean reaches along the shore is called LOW TIDE The vertical distance between low tides and high tides is called the TIDAL RANGE The tidal range varies depending on the shape and depth of the coastline The number of islands in the Philippine archipelago is rumored to vary depending on the tide

5. Time and tides Tide tables provide the times that low tide and high tide occur in any given area The time between consecutive high tides and low tides is approximately 6 hours and 20 minutes This time may vary slightly from place to place depending on the types of coastline

6. Tide Patterns SEMIDIURNAL TIDE refers to a tide pattern that has two highs and two lows each day The East Coast of the United States has this pattern DIURNAL TIDE refers to a tide pattern that has only one high tide and one low tide each day The Gulf Coast of the United States has this pattern MIXED TIDE refers to a tidal pattern with features of both semidiurnal and diurnal tides The West Coast of the United States has this pattern The first set of tides is stronger that the second set of tides each day

7. Galveston Tide Table

8. Gravity and Tides TIDAL BULGE represents high tides It is caused by the moon’s gravity pulling on the Earth http://www.linz.govt.nz/hydro/tidal-info/tidal-intro/cause-nature/images/day1.gif

9. Types of Tides Spring Tides Occur during the new moon and full moon The highest and lowest tides result from the combined pulling forces from the Earth, sun, and moon Neap Tides Weaker tides in which the tides are not as high or low as at other times of the month

10. Spring and Neap Tides Diagram http://csep10.phys.utk.edu/astr161/lect/time/tides.html

11. Waves

12. They are up-and-down movements of the ocean surface Mostly caused by wind blowing on the ocean’s surface

13. Factors that influence waves When the wind blows, it pushes on the ocean surface, causing the water to lift The size and speed of a wave is dependent on three factors: wind speed, the length of time it blows, and the distance over which it blows The greater are the size and speed of the wave it generates A gentle wind produces a small wave A strong wind produces a bigger wave

14. The Anatomy of a Wave http://www.google.com/imgres?imgurl=http://www.geo.umn.edu/courses/1006/Fall00_night/sine.JPG&imgrefurl=http://www.geo.umn.edu/courses/1006/Fall00_night/Week10_11.html&h=289&w =721&sz=118&tbnid=uMzYk3dCWoEJ::&tbnh=56&tbnw=140&prev=/images%3Fq%3Danatomy%2Bof%2Ba%2Bwave%2Bdiagram&hl=en&usg=__qmk-MqjZs8a_eLZOX- VVRwL99_8=&sa=X&oi=image_result&resnum=2&ct=image&cd=1

15. Wave Action A series of waves is called a WAVE TRAIN The speed (velocity) of a wave can be calculated if the wavelength and period (the time it takes for one wave to pass a given point)are known Formula: Velocity = wavelength/period SWELLS are formed when waves extend beyond the windy area in which they are generated They have longer periods and more rounded crests

16. Types of Waves Formed when the top of the wave which moves faster than its bottom pitches forward and crashes the water depth is less that one-half the wavelength Whitecaps are formed in the open seas when winds blow off the tops of narrow crests Rogue waves are formed when two or more large waves from a storm unite or when waves meet opposing currents Huge waves with very high crests and low troughs Rogue waves are dangerous and have caused the loss of many ships at sea

17. TSUNAMIS First recorded observation occurred on April 24, 1971 An 84 m high wave struck a chain of islands south of Japan Inaccurately called tidal waves Are not related to tides at all They are generated by seismic activity an undersea earthquake a landslide on the ocean floor a volcanic eruption

18. Currents

19. Highways of moving water that connect the continents Method of delivery for messages in bottles Driftwood from an offshore wreck washing onto the shore Definition: a large mass of continuously moving ocean water

20. The Major World Currents http://media-2.web.britannica.com/eb-media/57/70057-004-85830DA6.gif

21. The Coriolis Effect States that the spinning Earth causes the winds and surface waters to move in a clockwise direction in the northern hemisphere and in a counter clockwise direction in the southern hemisphere The ocean currents move in giant circles called GYRES Caused by the deflection of the ocean currents off of the continents Wind-driven ocean currents are also called SURFACE CURRENTS

22. Vertical Ocean Currents Subsurface currents Caused by temperature differences in the ocean water Warm water rises because its molecules are in motion making it less dense Cold ocean water is more dense so it sinks CONVECTION!!!!

23. Deep Ocean Currents COUNTERCURRENTS Warm water rises at the equator, flows until it cools, and then sinks at the poles Slow horizontal ocean currents that flow in a direction generally opposite to the wind-driven currents at the surface TURBIDITY CURRENTS Found along the continental slope where the seafloor around the continent drops off steeply Speed is due to the steepness of the slope UPWELLINGS Nutrients such as phosphates and nitrates are brought up from the bottom of the ocean by vertical currents

24. Wave and Tide Induced Currents UNDERTOW The returning currents or backwash from a wave breaking on shore Can have enough force to cause someone standing in the surf zone to fall RIP CURRENT Fast, narrow current of water moving seaward Caused when the pressure from the water accumulation on a sandbar forces it to break

25. Wave and Tide Induced Currents cont. TIDAL CURRENTS Produced when the tide enters and leaves bays and inlets Run parallel to shore Carry nutrients and small organisms back and forth between the bays and the offshore waters WHIRLPOOLS (aka eddies) The rapid movement of surface waters in a circle Usually happen between islands Occur when tidal currents move past each other in coastal waters or when ocean currents flow against tides or unusual coastal features