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Comment: 21:35 - 22:41 (01:06)
Source: Annenberg/CPB Resources - Earth Revealed 24, Waves, Beaches and Coasts
Keywords: ocean, wave, tide, Moon, Sun, Earth, gravity
Our transcription: Regardless of how the battle over seawalls and sediment supply eventually turns out, coastal dwellers will always have to deal with incursions from the oceans.
In addition to problems caused by crashing waves, there are a number of other factors that affect the level of the water.
The most familiar is the action of the "tides."
Tides are primarily the work of the moon, and to a lesser degree, the Sun.
As the moon orbits the Earth, it exerts a powerful gravitational pull.
This causes the ocean on the side of the Earth facing the Moon to bulge out slightly.
Another tidal bulge occurs on the other side of the planet as water lags behind due to weaker gravitational attraction.
These bulges create a high tide.
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