Why are there tides in Qiantang River?

Ocean tides are produced by the gravity of the moon, the sun and other celestial bodies. Under the action of gravity, the moon is attractive to the sea water on the earth. People call the force that attracts the high tide of seawater tidal force, and the distance between the earth's surface and the moon is different. Therefore, the tidal force of seawater varies from place to place. Generally, the place facing the moon has a large tidal force, while the seawater facing the moon has a small tidal force and a large centrifugal force. Elephants run with their backs to the moon, so there will be long tides. Because the celestial bodies are in motion, the tidal force exerted by seawater everywhere is constantly changing, which makes the seawater on the earth rise and fall, thus forming a tidal phenomenon.

The tide is very punctual. They are almost as accurate as clocks. The moon orbits the earth for 24 hours and 48 minutes, and the cycle of tides is also 24 hours and 48 minutes. During the day and at night, most of the sea water looks like the moon once, with its back to the moon once, and the sea water naturally fluctuates twice.

We know that the moon plays a leading role in tidal phenomena, but we can't ignore the influence of the sun. In the process of celestial movement, when the moon, the earth and the sun form a right angle, the tidal forces of the moon and the sun cancel each other out, and the fluctuation gap of the sea surface is very small. This is a small tide. When the sun, the moon and the earth are in a straight line, the tidal force of the moon is combined with the tidal force of the sun, and the tidal force is great. This is the spring tide. The earth is closest to the sun, and with the help of the moon, a special spring tide has formed. The world-famous Qiantang River spring tide occurred in the autumn equinox. Every time the tide rises, the Qiantang River will set off huge waves, such as Ma Benteng, which is breathtaking and spectacular, making it a must in the world.

Tidal changes directly affect people's lives, such as military affairs, ocean navigation, ocean fishing, mariculture, ocean engineering and various coastal production activities. In order to master the laws of tides, the research on tides has never stopped. There are many large and small ocean stations along the coast of China, which can record the changes of local tides and tidal levels at any time and transmit these information to the National Ocean Information Center in time and accurately. According to this information, experts in marine information make analysis and calculation, and make tidal schedules of China and major ports in the world, so as to know them three years in advance for use by various power generation departments.

Tides also contain huge energy, and tidal power generation is realized through tidal gaps. At present, more than ten tidal power stations have been built in China, and the Jiangxia tidal power station built in 1980 can generate1070,000 kwh per year. Because tidal power stations neither waste energy nor pollute the environment, they bring infinite light and benefits to people.