Moon and Sun gravitation moves Earth sea and land {tide}|. Earth gravity and land-and-sea elasticity oppose tides. Shallow-water tide motion makes heat by friction, which takes energy from Earth rotational energy. Earth rotation slows, making each day slightly longer. Earth-Moon distance increases slightly each day.
When Moon is overhead or on opposite side of Earth, continents rise up to six inches and oceans rise several feet {high tide}.
When Moon is to right or left, continents and oceans are at low height {low tide} {slack tide}.
When Moon is overhead or on opposite side of Earth and Sun is to right or left, high tides {neap tide}| are lower, at first-quarter or third-quarter moon.
When Moon and Sun are both overhead or opposite sides of Earth, tide {spring tide}| is extra high, at new or full moon.
Difference {tidal range} between high and low tide is 2 feet in sheltered bays, 5 to 10 feet on open coast, and 30 to 50 feet in V-shaped bays. Tidal currents flow 5 to 10 miles per hour.
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Date Modified: 2022.0225