What is tide?

Tides are caused by the gravity of the earth and the moon.

The gravity of the earth and the moon causes periodic movements and changes of the earth's lithosphere, hydrosphere and atmosphere, which are called "tides" and are divided into tides, tides and tides.

Most of the water is sea water, which will rise and fall under the gravity of the sun and the moon. Because the earth and the moon are in constant motion and the relative positions of the earth, the moon and the sun change periodically, the tidal force also changes periodically.

Water rotates with the rotation of the earth, and all rotating objects are subjected to a force. In ancient times, it was called tide during the day and sunseeker at night. Traditionally, the vertical fluctuation of sea surface is called tide, which is a natural phenomenon in coastal areas.