The sun, the moon and the earth line up in a straight line around the first and fifteenth day of each month in the lunar calendar. The gravity of the sun and the moon combine to attract the sea water on the earth's surface, so the tides on the first and fifteenth day of each month are relatively large. Especially around the Mid-Autumn Festival, it is the time when the earth is closest to the sun in a year, so the autumn tide around the fifteenth day of the eighth lunar month is the biggest in a year.
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Application of tides:
Application of Tide in Environmental Protection
Tidal energy is a kind of energy produced by the periodic fluctuation of seawater caused by tidal force. This is a kind of renewable energy, with huge reserves to be developed. The coastline of China is 32,000 kilometers long. Continental coastline 18000km, island coastline 14000km, rich in tidal energy resources. Tidal energy is clean and renewable, and can be recycled if used properly. It will greatly improve the energy consumption structure dominated by coal and reduce the harmful substances produced by primary energy combustion, which is of great significance to improve air quality.
2. The application of tides in natural disaster prevention.
In recent years, natural disasters have occurred frequently all over the world, causing huge casualties and property losses, such as the Indonesian tsunami in 2004, the tropical storm in Myanmar in 2008 and the Wenchuan earthquake in Sichuan, China, which made people pay more attention to the prediction of natural disasters. The law and function of tides is a complex geophysical problem, and tides and other natural phenomena play an important role in natural disaster prediction. It is more effective to collect more information and find the connection between them than to study natural disasters alone.
3. The application of tides in electric power.
The principle of tidal power generation, like ordinary hydropower generation, is a process of converting potential energy into kinetic energy and then into electrical energy through a certain height of potential energy difference. Tidal power generation must meet two conditions: the tide must be large and have enough potential energy; There must be a suitable geographical environment.
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