1. Chapter 10: Tides
Fig. 10-6
Fig. 10-7

2. Tide-producing forces
Gravity and
motions among
Earth, Moon,
and Sun
Fig. 10-2

3. Centripetal force “tethers” Moon to Earth
Directed away from barycenter
Fig a,b

4. Resultant tidal forces
Gravitational force, Earth and Moon
Centripetal force, Earth and Moon
Resultant force moves ocean water horizontally
Fig. 10-6
Fig. 10-7

5. Tidal bulges Two equal and opposite tidal bulges
Earth rotates beneath tidal bulges
Two high tides
Two low tides
Per day
Fig. 10-8

6. Complications to simplest equilibrium theory
Oceans do not cover entire Earth
Oceans do not have uniform depth
Friction between ocean and seafloor
Continents
Moon not always in same place with respect to Earth
Lunar day longer than solar day

7. Lunar day Moon revolves around Earth
Earth has to “catch up” with Moon to reach same position
Fig. 10-9

8. Time between successive high tides shifts day after day
Moon rises later each successive night

9. Solar tidal bulges
Tide-producing force of Sun less than half of Moon’s
Sun much farther away

10. Month tidal cycle Spring tides New Moon, Full Moon
Earth, Moon, Sun syzygy
Higher than usual high tides
Fig

11. Neap tide First Quarter, Last Quarter Earth, Moon, Sun quadrature
Lower than usual high tide
Fig

12. Declination of Sun and Moon
Orientation of Sun, Moon to Earth’s equator
Sun 23.5o N and S, yearly cycle
Moon 28.5o N and S, monthly cycle
Unequal tides
Successive tides different tidal range

13. Unequal tidal range
Fig

14. Elliptical orbits Perigee Apogee Lunar tidal force greater
Higher high tides
Apogee
Lunar tidal force lesser
Lower high tides
Fig

15. Dynamic theory of tides
Tide shallow-water wave
Speed varies with depth
Lags behind Earth’s rotation
Rotary flow in open ocean basins
Amphidromic point
Cotidal lines

16. Rotary flow Crest (high tide) rotates
Counterclockwise in Northern Hemisphere
Clockwise in Southern Hemisphere

17. Tidal patterns Diurnal Semidiurnal
One high, one low tide per lunar day
Period of tidal cycle 24 hours 50 minutes
Semidiurnal
Two high, two low tides per lunar day
Period 12 hours 25 minutes
Equal range

18. Mixed Most tides are mixed Two high, two low tides per lunar day
Unequal range
Most tides are mixed

19. Standing waves Forced standing wave caused by tides
Free-standing waves caused by strong winds or seismic disturbances
Fig

20. Node maximum horizontal flow Antinode maximum vertical flow
Fig

21. Bay of Fundy Largest tidal range (spring tide max 17 m) Shape of basin
Oscillation period close to tidal period
Shoals and narrows to north
Basin oriented toward right (Coriolis moves water toward right)
Fig

22. Tidal bores Wave created by tide rushes upstream Large tidal range
Low-lying coastal river
Max 8 m high
Fig. 10A

23. End of Chapter 10: Tides
Fig. 10-6
Fig. 10-7