Ch 11 Tides

1

• Ch 11 Tides
• Cause
• Variations with time
• Variations with location
• Dynamic vs. equilibrium model

50 ft difference between high and low tide at the
Bay of Fundy, Canada
2

• Flood tide
• Ebb tide
• Slack tide

Low tide High tide
(photos from Monroe and Wicander, 2001)
3
Gravitational force
Gravity of moon on water FT G m1 m2
r3 Inertia
4
Tides equilibrium theory

• Tidal day

5
Affect of moons orbit elliptic Moon above
equator
equator
Moon 28 1/2o north of equator
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(No Transcript)
7
December

• Affect of elliptical orbit
• Sun
• Aphelion
• Perihelion
• Moon
• Apogee
• Perigee

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Earth and Sun in line
Earth and Sun in line
days
Earth and Sun in line
Earth and Sun in line
days
Australia and New York not shown for same time
period
9
Dynamic theory of tides Semidiurnal tide Diurnal
tide Mixed tide
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Geographic distribution of three tide patterns
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Amphidromic point Link http//www.es.flinders.ed
u.au/7Emattom/IntroOc/lecture11.html
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Amphidromic points of earth Blue smallest tidal
range of crest amplitude Red highest tidal
range of crest amplitude
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Gulf of St. Lawrence
Ideal amphidromic point in wide confined basin
Actual amphidromic point at Southeastern Canada
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Low tide High tide
Bay of Fundy
Ideal tide in narrow confined basin
Actual tide in confined basin in Southeastern
Canada
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Tidal Bore in Qiantang River, China
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Intertidal zone Grunion run to spawn eggs on
Pacific Coast during spring and summer