1. Tides

3. Bay of Fundy ► Boats can only travel at higher tides ► Some of the highest tides in the world

4. High Tide

5. Low Tide

6. What causes tides? ► Tides are created by the imbalance between two forces: 1.Gravitational force of the Moon and Sun on Earth ► If mass increases (  ), then gravitational force increases (  ) ► If distance increases (  ), then gravitational force greatly decreases (  ) 2.Centripetal (center-seeking) force required to keep bodies in nearly circular orbits

7. Gravitational forces on Earth due to the Moon ► Force decreases with increasing distance. ► Watch: http://www.youtube.com/watch?v=Fhokv JZFURg http://www.youtube.com/watch?v=Fhokv JZFURg http://www.youtube.com/watch?v=Fhokv JZFURg

8. Centripetal forces on Earth due to the Moon

9. Resultant forces ► Resultant forces are:  The difference between gravitational (G) and centripetal (C) forces

10. Tide-generating forces ► Tide-generating forces are the horizontal component of the resultant force. Maximized along a “latitude” of 45º relative to the “equator”.

11. Tidal bulges Tide-generating forces produce 2 bulges: 1.Away from Moon on side of Earth opposite Moon 2.Toward Moon on side of Earth facing Moon Earth rotates in and out of tidal bulges, creating high and low tides. Watch: http://www.youtube.com/wa tch?v=5ohDG7RqQ9I http://www.youtube.com/wa tch?v=5ohDG7RqQ9I http://www.youtube.com/wa tch?v=5ohDG7RqQ9I

13. Relative sizes and distances on Earth, Moon, and Sun ► The Sun is much more massive than the Moon but much further away. Solar bulges are 46% the size of lunar bulges

15. The Moons Relation to Ocean Tides ► The height of the tides depends on the distance between the earth and the moon on a given day. ► Since the moon and the earth are not always the same distance apart, the tidal range changes daily. ► When the moon is farthest from the earth the lunar gravity is somewhat weaker.

16. ► Since the moon and the earth are not always the same distance apart, the tidal range changes daily. ► When the moon is farthest from the earth the lunar gravity is somewhat weaker.

17. The Monthly Tidal Cycle ► About every 7 days, Earth alternates between:  Spring tides (2)[Super Tides] ► Lunar and solar bulges add together ► Large tidal range ► Earth-Moon-Sun system at 180 0

18.  Neap tides (2)[No Tides ?] ► Earth-Moon-Sun system at right angles ► Lunar and solar bulges destructively interfere

19. Sun and Moon Influence Tides Together

20. Earth-Moon-Sun positions and the monthly tidal cycle

21. Tidal Patterns ► Diurnal  One high and one low tide each (lunar) day ► Semidiurnal  Two high and two low tides of about the same height daily ► Mixed  Characteristics of both diurnal and semidiurnal Not This!

23. Tidal patterns in the N.A

24. Tides in the ocean ► Shape and locations of coastlines creates irregular tides on our earth.

25. Tidal Patterns Vary with Ocean Basin Shape and Size The numbers indicate the hourly positions of tide crests as a cycle progresses. Dashed lines show the tide heights when the tide crest is passing.

26. Monthly tidal curves

27. The Bay of Fundy: Site of the world’s largest tidal range ► Super tides creates by shape and shallowness of Bay of Fundy (17meters )

31. Tidal bore = a true tidal wave ► Wall of water that moves upriver ► Caused by an incoming high tide ► Occurs in some low-lying rivers

35. Grunion and the tides ► Spawning cycles are timed precisely with the tides

38. Hurricanes and Tides

39. Hurricanes produce extra high tides called storm surges

42. Tides have high potential for tidal power generation

43. Power Plant at La Rance, France