Tides 2 31 Tides Tides are caused by the gravitational force of the moon and sun and the motion of earth The wavelength of tides can be half the circumference of earth Tides are forced waves because they are never free of the forces that cause them ID: 1021959
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1. 1 / 31Physical OceanographyTides
2. 2 / 31TidesTides are caused by the gravitational force of the moon and sun and the motion of earth. The wavelength of tides can be half the circumference of earth. Tides are forced waves because they are never free of the forces that cause them.
3. 3 / 31Moon TideProduced by the moon’s gravitation force on waterA bulge of water is created by the moon’s gravitational forceCentrifugal forces produces a bulge on the opposite side of the Earth & an area of low water between the tidal bulges
4. 4 / 31Source : Trujillo,Alan P., Essentials of oceanography / Al Trujillo, Harold Thurman. 10th ed
5. Lunar DayA lunar day is the time that elapses between when the moon is directly overhead and the next time the moon is directly overhead. 5 / 31
6. Spring TidesDuring the period of a new moon, the moon and sun are lined up on the same side of the EarthProduces the greatest range between high water and low water6 / 31
7. Neap TidesProduced when the moon is at a right angle to the line of centers of the Earth and the sunThe range between high and low water is small7 / 31
8. 8 / 31Tide PatternsDiurnal tideOne high and one low tide per daySemidiurnalTwice occurring high and low tide sequencesHigh and low tides are both at the same levelSemidiurnal mixed tideEach high tide reaches different heightsEach low tide falls to different levels
9. 9 / 31Tide PatternsThe worldwide distribution of the three tidal patterns.
10. 10 / 31Tide Patterns
11. 11 / 31Examples of monthly tidal curvesTop: Boston, Massachusetts, showing semidiurnal tidal pattern. Upper middle: San Francisco, California, showing mixed tidal pattern with strong diurnal tendencies. Bottom: Pakhoi, China, showing diurnal tidal pattern.Tide Patterns
12. 12 / 31Tide PatternsAmphidromic PointsA "no-tide" point in an oceanAbout a dozen amphidromic points exist in the world ocean. Sometimes called a node.
13. 13 / 31Amplitude is indicated by color, and the white lines are cotidal differing by 1 hr. The curved arcs around the amphidromic points show the direction of the tides, each indicating a synchronized 6 hour period. R. Ray, TOPEX/Poseidon: Revealing Hidden Tidal Energy en:GSFC,en:NASA
14. Animated map of the tidal nodes of the Earth14 / 31
15. 15 / 31Tides in a Confined BasinTidal ranges vary across the ocean basinLargest variations occur at the edgesEspecially in bays and inletsEnergy is concentrated in a small areaA mini amphidromic system developsExtreme tides in areas where there are natural oscillation periods of 12 or 24 hours
16. 16 / 31Tides in Confined BasinsThe tidal range is determined by basin configuration.
17. 17 / 31Tides in a narrow basin. Note that a true amphidromic system does not develop because space for rotation is not available.Tides in Confined Basins
18. Bay of Fundy, Nova ScotiaWorld’s Largest Tidal Range18 / 31Spring Tide Timelapse, Halls Harbour Video: https://youtu.be/hbzwzrZXUKA
19. 19 / 31The tide was rising in the Bay of Fundy when the two MODIS sensors (on the Terra and Aqua spacecraft) flew overhead on April 15, 2009. Terra flew by a little over an hour after low tide, and Aqua flew past an hour and 47 minutes later.
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21. 21 / 31Tidal Bore - A true tidal wave "River Ribble bore" by Frangle Plazma Goat - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons
22. Tidal terms & currents22 / 31
23. Tides and Marine Organisms23 / 31
24. 24 / 31Tides and Marine OrganismsGrunions! (Leuresthes tenuis)Spawn from late February to early September
25. 25 / 31
26. 26 / 31Tidal PowerTidal energy can be exploited in two ways:By building semi-permeable undersea tidal turbines across estuaries with a high tidal range.By harnessing offshore tidal streams
27. 27 / 31Tidal Power
28. 28 / 31CountryPower StationTidal Loss (m)Capacity (MW)Operated SinceFranceLangce8.52401966CanadaAndeboriece7.119.11984Former Soviet UnionGicelaya3.90.41968ChinaJiangxia5.13.21980ChinaBaishakou2.40.641978ChinaXingfuyang4.51.281989ChinaYuepu3.60.151971ChinaHaishan4.90.151975ChinaShashan5.10.041961ChinaLiuhe2.10.151976ChinaGuozishan2.50.041977List of World Main Tidal Power Stations
29. 29 / 31Tidal PowerLa Rance, France - world's first tidal power plantAverage tidal range 27 feetDam encloses 8.5 sq. milesCapacity is 320,000 KW
30. 30 / 31Tidal PowerLow Production but also Low Environmental ImpactNo noxious wasteNo consumption of resourcesMinimum disturbance to scenery
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