When the tide is high, the tide flows from the sea towards the shore. Tidal waves propagate from east to west, in the direction of diurnal movement. The time taken for a rise and fall of the tides is half a lunar day, or 12 hours and 25 minutes. This is also called the semi-diurnal tide. By the sea, you experience it every day. You can see the sea water rising and falling twice regularly.
Actual tides are also limited by many factors such as geographic environment, coastal location and the movement of ocean currents. Take the Qiantang River tide as an example. Hangzhou Bay, at the mouth of the Qiantang River, is trumpet-shaped and becomes narrower as it goes deeper. In addition, sediments brought in at high tide accumulate at the bottom of the river. to form a sand sill, causing a rise in the tide.
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The principles of tidal power generation are similar to those of hydropower generation, that is, the potential energy of the level difference of water generated by the rise and fall of the tide is converted into mechanical energy, and then the mechanical energy is converted from mechanical energy to electrical energy. Someone has calculated that the world's reserves of tidal energy are approximately 2.7 billion kilowatts. If they are all converted into electrical energy, the annual electricity production will reach about 1.2 trillion degrees.
Tidal energy is not only non-polluting, but also has advantages over renewable energy sources such as wave energy, wind energy and solar energy. It can produce electricity continuously, while wave and wind energy. Solar energy and solar energy canent produce electricity to a greater extent affected by climate.
There are therefore generally two tides per day. During the course of a day, except for the North and South Poles and some regions, tides everywhere on earth rise and fall twice, each cycle lasts 12 hours and 25 minutes, twice a day, a total of 24 hours and 50 minutes, so the tides rise and fall. The time is pushed back by 50 minutes each day.
It is precisely because of such fluctuations that when sea water rises somewhere, stagnant water elsewhere temporarily replenishes it, thus forming a tidal current, conducive to the exchange of environments of sea water. When the tide rises, it is not because there is more water, but because the sea water offshore is moving towards land in waves under the gravitational force of the moon , forming a tide. it looks like the sea water has risen.