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7 Cards in this Set
- Front
- Back
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movement of ocean water |
Horizontal motion : Ocean Currents Waves Vertical motion : Tides Twice a day
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Waves |
Actually the energy, not the water as such. When the depth of the water is less than half the wavelength of the wave, the wave breaks. Largest waves are found in the open oceans. Steep waves : young ones.. Formed by local winds. Waves travel because wind pushes the water body in its course while gravity pulls the crests of the waves downwards. Wave amplitude : One half of the wave height. Wave period : Time interval between two successive wave crests or troughs. Wavelength : horizontal distance between two successive crests. |
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Tides |
Surges : Movement of water caused by meteorological effects - winds, atmospheric pressure. Are not regular like Tides. Another factor that effects Tides is the centrifugal force, which is the force that acts to counter the balance of gravity. On the side of the earth facing the moon, a tidal bulge occurs. While on the opposite side though the gravitational attraction of moon is less as it is farther away, the centrifugal force causes tidal bulge. Some facts: 1. The tidal bulges on wide continental shelves have greater height. 2. When tidal bulges hit the mid oceanic islands they become low. 3. The shape of bays and estuaries along the coastline can also magnify the intensity of Tides. Tidal Currents : When the tide is channeled between islands or into bays and estuaries. |
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Tides of Bay of Fundy, Canada |
The highest Tides in the world. Facts: There are 2 high Tides and 2 low Tides every day - 24 hours. Thus a tide must come in within about a six hour period. |
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Tides based on frequency Semi-diurnal tide |
1. Most common 2. Two high and two low each day 3. Successive high or low Tides are approximately of the same height. |
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Diurnal tide |
1. Only one high tide and one low tide during each day. 2. Same height. |
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Mixed tide |
Variations in height. Occur : 1. West coast of North America 2. Many islands of Pacific Ocean |
