Why do low tides and high tides 5, why do low tides and high tides

The sea water rotates with the rotation of the earth, and the rotating objects are subjected to centrifugal force, which makes them tend to leave the center of rotation, just like a rotating open umbrella, and the water droplets on the umbrella are about to be thrown out. At the same time, seawater is also attracted by the Moon, the Sun and other celestial bodies, and the Moon is more attractive because it is closest to the Earth. In this way, the seawater forms a tidal attraction under the combined action of these two forces.

Because the earth and the moon are constantly moving, the relative positions of the earth, the moon and the sun are changing periodically, so the gravitational force is also changing periodically, which makes the tidal phenomenon occur periodically.

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The high tide and low tide, the so-called tides, are related to the moon. Generally speaking, the side facing the moon on the earth will rise because of the gravitational pull of the moon, and the side facing the moon will also rise because the moon has the least gravitational pull on it towards the center of the earth, which is called high tide. And perpendicular to the moon-geocentric line, the water level is the lowest, and that's the low tide. In addition, the sun also has an influence on it.

When the sun, the moon, and the earth are approximately in a straight line, the force is the greatest, which generally occurs on the first or fifteenth day of the lunar calendar, and some places are called tides; And when they're at right angles, the tide rises and falls the least, and it's a small tide.

High tide and low tide are the manifestations of tides. It has been said that tides are the breath of seawater. Of course, this is a more poetic interpretation.

Tides, mainly because of the periodic movement of the movement of the sea water under the action of the gravitational force of celestial bodies. The gravitational force refers to the resultant force of the gravitational force of the earth and the inertial centrifugal force generated by the earth's motion around the common center of mass of an object on the earth. It is directly proportional to the mass and inversely proportional to the cube of the distance.

Of course, scientists throughout history have also proposed the theory of equilibrium tides and the theory of tidal dynamics to explain it. You can refer to the following. Generally, when the Sun, Moon, and Earth are approximately in a straight line, the force is the greatest, which occurs on the first or fifteenth day of the lunar calendar, called the tide; And when they are at right angles, the tide rises and falls the least, i.e., small tides.

The tides are mainly made by the Moon"Tide gravitation"caused. This"Tide gravitation"It is the resultant force of the gravitational pull of the Moon on the ground and the inertial centrifugal force of the Earth's rotation.

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The causes of high and low tides are: Earth's gravity, wind, seafloor topography, seasonal variations, ** and tsunamis.

1. Earth's gravity.

Earth's gravitational pull is one of the most important causes of high and low tides. Under the gravitational pull of the moon and the sun, the sea water is pulled by gravity, forming high tides and low tides. The Moon's gravitational pull on the Earth is greater than that of the Sun, so the Moon's influence on high and low tides is more significant. Rent state.

2. Wind power. Wind is also one of the factors that affect high and low tides. When the wind blows over the sea, waves are formed, and these waves affect the height of the seawater, which affects the high and low tides. Both the size and direction of the wind and waves affect the height of the seawater.

3. Submarine topography.

The topography of the seabed can also affect the high and low tides. On the coastline, if the seafloor topography is slope-shaped, the water rises higher at high tide and drops deeper at low tide. On the other hand, if the topography of the seabed is flat, the amplitude of high and low tides will be smaller.

4. Seasonal changes.

Seasonal changes can also affect high and low tides. In summer, the sun's exposure will increase the temperature of the seawater, which will increase the expansion coefficient of the seawater, reduce the density of the seawater, and increase the height of the seawater. In winter, when the temperature of the sea decreases, the expansion coefficient of the sea decreases, the density of the sea increases, and the height of the sea water decreases accordingly.

5. ** and tsunamis.

** and tsunamis can also affect high and low tides. When a tsunami occurs, the sea water is subjected to strong vibrations, resulting in the formation of huge waves, and the height of the sea water rises or falls accordingly. In this case, the high and low tides will be more intense than usual.

High tide is the phenomenon of rising sea water due to changes in the water level of the ocean. There are three main reasons for this:

1. The gravitational effect of the sun and the moon on the seawater: The gravitational effect of the sun and the moon on the earth will cause the sea surface to fluctuate at a certain height and form tides. On the Earth's surface, tides affect coastlines to varying degrees at different times, causing the water to rise from low to high.

2. Changes in atmospheric pressure: atmospheric pressure has a certain effect on seawater. As the weather changes or the weather system moves, the pressure of the seawater also changes, resulting in the high or low tide of the seawater.

3. Wind effect of seawater: Wind can affect the flow and rise and fall of seawater. When the wind is strong, it pushes the sea water and causes it to move in the direction of land, so high tides may occur near the coastline, especially in weather conditions such as storms.

In summary, the main causes of high tides are the gravitational effect of the sun and moon on seawater, the change of atmospheric pressure, and the wind effect of seawater.

High tides are a phenomenon that occurs due to the gravitational pull of the moon and the sun on the tides on Earth. There are two main reasons for this phenomenon:

1.Lunar gravity: As the lunar spine orbits the Earth, the gravitational force causes a strong tidal force on the Earth.

This gravitational pull pulls on the ocean's water column to form a tidal wave that follows the position of the Moon. When the tidal wave accumulates to a high enough degree, the phenomenon of high tide is formed. In addition, due to the rotation of the Earth, the gravitational attraction will vary from region to region at different times, which leads to differences in the timing of high tides in different locations.

2.Solar gravitational pull: Although the gravitational pull of the sun has a relatively small effect on the earth, it also contributes to tidal phenomena.

When the Earth, the Moon, and the Sun line up in a straight line (as during a new moon and a full moon), the Sun's gravitational pull enhances the tidal effects caused by the Moon's gravity, resulting in greater high tides.

Therefore, the phenomenon of high tides is mainly due to the combined action of the gravitational pull of the Moon and the Sun. The timing and height of high tide in different regions are affected by factors such as topography, seafloor topography, and the rotation of the Earth.

The high and low tides are different in every place and every day.

But there's a general pattern. Fishermen by the sea have a proverb about the ebb and flow of tides:

On the fifteenth day of the first month, the tide falls at noon, and the tide falls on five and six.

The meaning of the first sentence is that the first and fifteenth days of the lunar calendar are tides at 12 o'clock (including noon and midnight), and each day is delayed by 50 minutes (because 12 hours are divided equally among the fifteen days).

The meaning of the second sentence is that the high tide process is 5 hours, and the low tide process is 6 hours (the high and low flat tides also take more than 1 hour), adding up to a high and low tide cycle of about 13 hours.

Since fishermen do not need a very precise time to go to sea, the above is only an approximate time, and the exact time should be read by the State Maritime Administration's tide forecast.

Generally speaking, there are two causes of high tide and low tide, which are the rotation of the earth itself and the gravitational interference of external celestial bodies, such as the tidal force caused by the sun and the moon. High tide and low tide refer to a natural phenomenon caused by the disturbance of external forces in the seawater covering the earth's surface.

The following is an introduction to the causes of high and low tides from the perspectives of the sun and the moon.

Tides caused by the Moon.

As for how does the moon affect the ebb and flow of tides? It is necessary to understand the law of gravitation, because the sea water can flow, so when the moon appears in the sky above any part of the earth, it will attract local water, and when the moon leaves, the water that is sucked up will flow away, and the seawater will form a scene where we see the high tide and the ebb and flow.

The gravitational pull of the moon attracts not only the sea water facing the moon, but also the sea water that does not face the moon. But the farther away you are from the moon, the less gravitational pull you will experience. So, the gravitational pull on the side of the Earth near the moon is greater, and the gravitational pull on the back side is relatively smaller, so that we will see two tides a day, the high tide in the morning is called the tide, and the high tide in the evening is called the tide.

Tides caused by the sun.

Because the Earth is in the orbit of the Sun planet, it is similar to the large water balloon demonstrated in the Space Mentoring Class, that is, the Earth is weightless to the Sun. Weightlessness makes the Earth immune to the gravitational pull of the Sun, so that the Sun does not exert tidal forces on the Earth. However, the diameter of the earth is 12,700 kilometers, so the difference in the altitude of the limb and land orbits is 12,700 kilometers, so the vector parameters of the equilibrium point are different, and this difference makes the earth on the solar side produce a slight tidal force phenomenon.

Because the earth and the moon are constantly moving, the relative positions of the earth, the moon and the sun are changing periodically, so the gravitational force is also changing periodically, which makes the tidal phenomenon occur periodically, which is the reason for the ebb and flow of the tide.

Seawater also rotates with the rotation of the Earth, and the rotating objects are subjected to centrifugal force, which makes them have a tendency to leave the center of rotation: at the same time, seawater is also attracted by the Moon, the Sun and other celestial bodies, because the Moon is closest to the Earth, so the attraction of the Moon is greater. In this way, the seawater forms a tidal attraction under the combined action of these two forces.

The Moon, commonly known as the Moon, also known as Taiyin and Xuantu in ancient times, is the only natural satellite of the Earth and the fifth largest satellite in the solar system.

The sun is the central body of the solar system and occupies the overall mass of the solar system.

Earth (English name: earth; Latin: Terra) is the third closest planet to the Sun and the only known object that harbors and supports life.

Because the earth revolves around the sun and the moon revolves around the earth, these two planets are sometimes very close to the earth, and the gravitational force will become very large, and the gravitational force is slowly changing, so the sea water is attracted, and there are tides and tides. Hope to adopt.

The main reason for the high and low tides is the gravitational pull of the moon. The rise and fall of the sea water occurs during the day and is called the tide during the day, and it is called the tide at night, so it is also called the tide. It is said in ancient Chinese books"The water of the sea is the tide in the morning and the tide in the evening"。.

There is a period of time between high tide and low tide when the water level does not rise or fall, which is called flat tide.

The sea will be ** at high tide, and the sea level will be rolling, and the scenery is spectacular. When the tide is low, the water quietly recedes, revealing only a stretch of beach. According to common sense, there are usually two high tides and low tides a day.

Although the high and low tides are due to tidal forces, these tidal forces can also cause other astronomical phenomena. For example, the tidal force of the Earth on the Moon causes the Moon's rotation to gradually slow down, forming a tidal locking phenomenon, so that people can only see the front side of the Moon on Earth.

The rise and fall of sea water is related to the gravitational pull of the moon, and the sea water is attracted by the moon and has high and low tides. Because the earth's surface or fiber points are different from the moon, the gravitational force is different, and the gravitational force of the place facing the moon is larger, and the sea water will expand outward; Although the gravitational pull on the place with its back to the moon is small, the centrifugal force of the Earth itself becomes larger, so it also expands. At this time, the oceans on the earth's surface have high tides with rising water levels and low water levels.

Due to the rotation of the Earth, the phenomenon of rising water levels will periodically propagate to the east and west, and of course the gravitational pull of the sun will also have an effect on the oceans, but the effect is much smaller than that of the moon. To sum up, the main reason for the fluctuation and fall of sea water is the combined force of the moon's gravity and the earth's centrifugal force.

Analysis of the principle of sea water fluctuations.

To put it simply, the distance between the moon and the earth is too far, and the front of the sea water is just facing the moon or the group, under the action of the tidal force produced by the moon on the earth, the force at this time is the largest, so the phenomenon of sea water ** will occur, and when the sea water is not facing the moon, but obliquely facing the moon, the sea water will be under the action of the tidal force, and the phenomenon of sea water withdrawing will occur, which is the low tide we see.