2. Tides: Sun, Moon, Rise and Fall Geosc040, April 5, Lecure 22 ‪DJ Twisted Turn The Tide Remix‬ Island Song Zac Brown Band King of the Beach Wavves The Front Bottoms - Twelve Feet Deep Thanks to Samuel K.

3.  Do you find yourself dreaming about the ocean? Join the Marine Science Society!! (MSS) Check out our Facebook page: Penn State Marine Science Society http://www3.geosc.psu.edu/Courses/Geosc040/

4. Quiz 2: On Apr. 13 OLA 10 Due today, 5 Apr Extra Credit Letter due tomorrow, 6 April OLA 11 Due Thursday, 7 Apr Homework 4 Due Apr. 19 Read about the ocean

5. Types of Waves Defined in terms of Water Depth Only some of the molecules in the water column are involved in a deep-water wave…

6. Shallow-Water Waves Speed is related to water depth d: S =(g d) 1/2 Waves are slower in shallower water: d=10 m, s=10 m/s; d=5 m, s=7 m/s; d=1 m, s=3.2 m/s piru.alexandria.ucsb.edu/~tierney Wavelength (L) and speed (S) decrease while period T remains constant S = L/T

7. Today’s Clicker Questions A.I will receive full credit for answering 80% or more of the questions B.I will receive no credit if I answer less than 80% of the questions C.If there are 10 questions and I answer at least 8 of them I’ll get full credit for today (100%); If I answer 7 or fewer questions, I will receive no credit for today. D.If I answer the question correctly I’ll get a bonus point, up to a maximum of 105% for today’s in-class exercise E.All of the above (this is the correct answer, choose E!)

8. My Job in Geosc040 100 Thomas is a big room. Talking is distracting to your neighbors… Wait for clicker questions Don’t chat during lecture slides

9. Origin of Tides Two Approaches 1)Equilibrium theory. Makes simplifying assumptions, provides a basic understanding of tides 2) Dynamic theory. Complexities of coastlines, bays, ocean basin geometry, Earth deformation.

10. Mont St. Michel

11. 1)Mont St. Michel

12. Bay of Fundy, Nova Scotia

14. Low Tide High Tide

15. Low Tide High Tide

16. Low Tide High Tide Equilibrium theory of tides: we can think of the tidal bulges as stationary during a given day. So points on Earth rotate under them, creating two highs and two lows per day.

17. Semidiurnal: Two high tides and two low tides each day X X X X

18. Some Definitions Flood Tide: Rise of water level Ebb Tide: Fall of water Types of tides (observed in tidal records): Semidiurnal – approx. twice a day (12hrs 25min) example: east coast of US Diurnal - once a day (24hr 50min) example: Gulf coast of US Mixed tides - usually twice a day but varying amplitude example: Pacific coast of US

19. Earth Spins, Moon Orbits 24hr 50min tidal cycle relates to the moon's orbit and spin of Earth As Earth spins in a 24 hr period, the moon has advanced in its orbit by about 13 degrees (lunar cycle takes 27.55 solar days) 50 minutes accounts for the time it takes a point on Earth to return to the original position directly under the moon.

20. Small “Tall" Medium “Grande“ Large “Venti” 24hr 50min tidal cycle relates to the moon's orbit and spin of Earth As Earth spins in a 24 hr period, the moon has advanced in its orbit by about 13 degrees (lunar cycle takes 27.55 solar days) 50 minutes accounts for the time it takes a point on Earth to return to the original position directly under the moon.

21. Three main types of Tides Worldwide distribution

22. Gravity is proportional to mass R 2 Tides are a product of Gravitational forces and Inertial (or Centrifugal) forces

23. Tides are produced by the Moon and the Sun Tidal forcing is proportional to: mass R 3 (3.8x10 8 ) 3 [m 3 ] 7.4x10 22 [kg] = 0.0013 Moon: (1.5x10 11 ) 3 [m 3 ] 2.0x10 30 [kg] = 0.0006 Sun: The Moon has about 2x the effect of the Sun Tides are a product of Gravitational forces and Inertial (or Centrifugal) forces

24. Spring tide Neap tide

25. http://www.fearofphysics.com/SunMoon/sunmoon1.html

26. http://aa.usno.navy.mil/cgi-bin/aa_moonphases.pl?year=2016&ZZZ=END Time is “Universal Time” or “GMT” Phases of the moon, 2016

27. Why does tidal amplitude vary throughout the month? Spring tides and Neap Tides. The Sun and Moon!

28. Why does tidal amplitude vary throughout the month? Spring tides and Neap Tides. The Sun and Moon!

29. Spring tide: The Sun and Moon Work together Spring tide Neap tide Neap tide: The Sun and Moon oppose one another

30. Tides are produced by Gravity and Centrifugal force Centrifugal force results from Inertia and rotation Why are there Two Tidal Bulges!

31. Tides are a product of Gravitational forces and Inertial (or Centrifugal) forces Centrifugal forces Gravitational forces Both Earth and the Moon revolve around this axis every 28 days Center of Mass for the Earth- Moon system

32. Centrifugal forces = m  2 r Angular velocity  Tides are a product of Gravitational forces and Inertial (or Centrifugal) forces Inertial force

35. Why are there Two Tidal Bulges!?? -Gravity and Inertia (centrifugal force)

36. Equilibrium Theory of Tides: Tides stay in place -- and Earth rotates beneath them…

37. Semidiurnal: Two high tides and two low tides each day X X X X

38. Fig 10.13 Global Distribution of Tide Types Note dominance of Semidiurnal tides

39. Origin of Tides Two Approaches 1)Equilibrium theory. Makes simplifying assumptions, provides a basic understanding of tides 2) Dynamic theory. Complexities of coastlines, bays, ocean basin geometry, Earth deformation.

44. Note Asymmetry in highs and lows

45. A

46. Timing and Predictability of Tides Semidiurnal tides have a range that cycles over a 14 day period. This coincides with the moon’s 28 day orbital period. Monthly inequality Max semi-diurnal tides occur when spring tides coincide with lunar perigee. Predicting tides is difficult Factors to consider: lunar distance solar distance lunar declination solar apparent declination relative alignment of sun and moon coastal morphology location of amphidromic point must also take into account storms, wind patterns, etc.

47. Tidal Regimes Macrotidal Mont St. Michel, France

48. Dynamic theory of Tides and Amphidromic points Continental margins and the Coriolis effect 1) Continents. As Earth spins the tidal bulges attempt to stay below the moon and opposite of it. Therefore water is forced against the continental margin. This occurs on the western margin of the ocean basin (eastern margin of continent) Tides are very long-wavelength shallow water waves. Tidal crests are separated by half of Earth’s circumference! Picture waves trapped in ocean basins between continents. 2) Coriolis. In the northern hemisphere, as water travels north it moves to the right and thus the Eastern side of the ocean basin. The opposite happens for water traveling south. This sets up a counterclockwise wave motion, with water sloshing back and forth in the ocean basins. Like Fig 10.14

49. Dynamic theory of Tides and Amphidromic points Continental margins and the Coriolis effect Development of Amphidromic Circulation