Lecture 25 - Tides Atmosphere

Lecture 25 - Tides Atmosphere - Lecture 24 Waves Test...

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Lecture 24 Waves
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Test Thursday December 1 Chapters 8 Geologic Time 9 Earth Origin part of chapter 10 History of Continents 11 Geobiology 19 Deserts 20 Oceans 21 Glaciers Plus extra material presented in class on Oceans through and including November 22. Bring your ID Old Tests on T-square
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Tides Gravitational forces of moon and sun Equilibrium theory of Tides Dynamic theory of Tides (Reality): tidal patterns,  confined basins
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Equilibrium Theory Tides are always in equilibrium with the gravitational pull of the moon and Earth is a planet covered in water. Assumption
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Gravity and centrifugal force (also called “ tractive forces ”) Together:The earth-moon system Equilibrium theory of tides
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Tides: The moon and the sun together Spring tide Neap tide
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Moon travels around the Earth Tidal cycle is 24h 50 min because the moon is traveling around the Earth in the same direction that the Earth spins at a rate of once every 29.5 days. 1/29.5day = 0.034day 0.034 day = 50 minutes So each day, the high tide is 50 minutes later .
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Timing of the tides? How many Tides in a day?
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Semidiurnal tides occur twice in a lunar day Diurnal tides occur once each lunar day Mixed tides describe a tidal pattern of significantly different heights through the cycle Amphidromic points are nodes at the center of ocean basins; these are no-tide points.
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Dynamic Theory Waves travel at a fixed waves speed There are continents and rotation Needs to account for:
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Red = High Blue = Low Whole Earth
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Animation of Tidal Elevations in the Pacific
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Inertia + continents cause the tidal motion on the planet to  differ markedly from the “motion” of the forces. We can calculate the water motion knowing the forces, but  we cannot say that the shape of the water is the same as  the “shape” of the forces. For this reason tides must not be visualized as bulges  standing under the sun and moon. But rather as very long waves over the sea forced by the  gravitational-centrifugal forces associated with the moon- sun-earth system.
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Tides in confined basins Increase tidal range (the difference  between high and low tide) Examples --Bay of Fundy, Canada --Northern Gulf of California, Mexico  • Tidal bores - wave of water moving  upstream - result of high-tide crest  entering confined inlet
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Bay of Fundy: map 2.416
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Large Tidal Range Bay of Fundy: extreme tides because water in narrow bay seiches at the same frequency as the lunar tides.
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A view of the tides at Halls Harbour on Nova Scotia's Bay of Fundy. Tidal range 15 m
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Lecture 25 - Tides Atmosphere - Lecture 24 Waves Test...

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