The tides encompass both high tide, when the sea level rises above normal levels,and low tide, when it falls below them. This is caused by the Moon's (and to a lesser extent, because it is so much further away, the Sun's) gravity affecting the ocean, similarly the Earth's rotation is also involved. Basically, as the Earth turns, and sections rise. The Earth's own centrifugal force helps 'fling' seawater upwards. Of course, this water has to come from somewhere, and as sea levels rise in some places, they recede in others.
GRAVITY AND CENTRIFUGAL FORCE WORK TOGETHER TO PRODUCE TIDES
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