At first, under the tidal force of the sun, the moon and other stars, the sea surface will rise and fall regularly: in a certain period of time, the sea surface will rise sharply to a higher height, and then the rising sea surface itself will be timid, leaving a beach and producing a low tide. That kind of constant, it is not easy to stop from beginning to end. This kind of underwater exercise and fitness is tide. Long-term fluctuation of sea surface under the action of tidal force. In the vertical direction, it is reflected in the rise and fall of tidal level and the change of tidal trend.

The fluctuation of tides is closely related to our various activities: ships sailing and entering and leaving ports, ships, agriculture, aquaculture, salt industry, aviation logistics, geodesy and coastal green ecological environment protection are all trying their best to grasp the periodicity of tidal changes. In addition, the application of tidal power generation capacity is also an important aspect of energy development trend.

Factors of production, the attraction of the moon, sunshine or other stars to the company's quality products on the earth, and the attraction to the core company's quality products. The specifications of the tidal force of an object to a point on the earth are directly proportional to the mass of the object, inversely proportional to the square of the distance from the center of the earth to the core of the star, and also related to the zenith distance where the star is located (the closer the zenith distance is to 90, the smaller the tidal force is).

Therefore, the specifications and direction of tidal force on the earth are different from time to time. Although the mass of the sun is much larger than that of the moon, its tidal force is only 46% of that of the moon because it is far from the earth. Compared with the moon and sunlight, the tidal force of other stars on the earth is very small and can be ignored. Tides caused by the tidal force of the Moon,

Call it the moon tide; It is caused by the sun's tidal force, which is called the solar tide. Both belong to astronomical tide. It not only causes seabed tides, but also continues to cause tides (surface tides) and gas tides (gas tides) to appear again on the solid earth. As far as the seabed is concerned, the tide is below the earth's tide and the tide is above the water surface, both of which have a bad influence on the ocean.