Outflow of water. The phenomena of the ebb and flow of the sea. The largest amplitudes of tides

There is a rise and fall of water. This is a phenomenon of the ebb and flow of the sea. Already in ancient times, observers noticed that the tide comes some time after the climax of the moon at the place of observation. Moreover, the tides are strongest on the days of new and full moons, when the centers of the Moon and the Sun are located approximately on the same straight line.

Taking this into account, I. Newton explained the tides by the action of gravity from the Moon and the Sun, namely, by the fact that different parts of the Earth are attracted by the Moon in different ways.

The Earth revolves around its axis much faster than the Moon revolves around the Earth. As a result, the tidal hump (the relative position of the Earth and the Moon is shown in Figure 38) moves, a tidal wave runs across the Earth, and tidal currents arise. When approaching the shore, the wave height increases as the bottom rises. In inland seas, the height of the tidal wave is only a few centi-meters, in the open ocean it reaches about one meter. In favorably located narrow bays, the height of the tide increases several times more.

The friction of water against the bottom, as well as deformations of the Earth's solid shell, are accompanied by the release of heat, which leads to the dissipation of the energy of the Earth-Moon system. Since the tidal hump is due to the east, the maximum tide occurs after the climax of the Moon, the attraction of the hump causes the Moon to accelerate and slow down the Earth's rotation. The moon is gradually moving away from the Earth. Indeed, geological data show that in the Jurassic period (190-130 million years ago) the tides were much higher, and the day was shorter. It should be noted that when the distance to the Moon decreases by 2 times, the tide height increases by 8 times. Currently, the day is increasing by 0.00017 s per year. So after about 1.5 billion years, their length will increase to 40 modern days. The month will be the same length. As a result, the Earth and the Moon will always face each other by the same side. After that, the Moon will begin to gradually approach the Earth and in another 2-3 billion years will be torn apart by tidal forces (if, of course, by that time the Solar System will still exist).

The influence of the moon on tide

Consider, following Newton, in more detail the tides caused by the attraction of the Moon, since the influence of the Sun is significantly (2.2 times) less.

Let's write expressions for the accelerations caused by the attraction of the Moon for different points on the Earth, taking into account that for all bodies at a given point in space, these accelerations are the same. In the inertial frame of reference associated with the center of mass of the system, the acceleration values ​​will be:

A A = -GM / (R - r) 2, a B = GM / (R + r) 2, a O = -GM / R 2,

where a A, a O, a B- accelerations caused by the attraction of the moon at points A, O, B(fig. 37); M- the mass of the moon; r- radius of the Earth; R- the distance between the centers of the Earth and the Moon (for calculations, it can be taken equal to 60 r); G- gravitational constant.

But we live on Earth and all observations are carried out in a frame of reference connected with the center of the Earth, and not with the center of mass of the Earth - the Moon. To go to this system, it is necessary to subtract the acceleration of the center of the Earth from all accelerations. Then

A ’A = -GM ☾ / (R - r) 2 + GM ☾ / R 2, a’ B = -GM ☾ / (R + r) 2 + GM / R 2.

Let's perform the actions in brackets and take into account that r little in comparison with R and in sums and differences, it can be neglected. Then

A ’A = -GM / (R - r) 2 + GM ☾ / R 2 = GM ☾ (-2Rr + r 2) / R 2 (R - r) 2 = -2GM ☾ r / R 3.

Acceleration a’A and a’B equal in magnitude, opposite in direction, each directed from the center of the Earth. They're called tidal accelerations... At points C and D tidal accelerations, smaller in magnitude and directed to the center of the Earth.

Tidal accelerations are the accelerations arising in the frame of reference associated with the body due to the fact that, due to the finite dimensions of this body, its different parts are differently attracted by the disturbing body. At points A and B the acceleration of gravity turns out to be less than at the points C and D(fig. 37). Therefore, in order for the pressure at the same depth to be the same (as in communicating vessels) at these points, the water must rise, forming the so-called tidal hump. Calculations show that the rise of water or tide in the open ocean is about 40 cm. In coastal waters it is much higher, and the record is about 18 m. Newtonian theory cannot explain this.

On the coast of many outer seas, you can see a curious picture: along the coast, not far from the water, there are fishing nets. Moreover, these nets were not supplied for drying, but for fishing. If you stay on the shore and watch the sea, then everything will become clear. Now the water begins to arrive, and where there was a sandbank just a few hours ago, waves splashed. When the water receded, nets appeared, in which the tangled fish sparkled with scales. The fishermen, going around the nets, took the catch. Material from the site

This is how an eyewitness describes the onset of the tide: “We got to the sea,” a fellow traveler told me. I looked around in bewilderment. There really was a coast in front of me: a trail of ripples, a half-buried seal skeleton, rare pieces of fin, fragments of shells. And then there was an even space ... and no sea. But three hours later the motionless line of the horizon began to breathe, became agitated. And now the sea swell sparkled behind her. The tide shaft rolled uncontrollably forward across the gray surface. Overtaking each other, the waves ran ashore. One after another, the distant rocks sank - and only water is visible all around. She throws salt spray in my face. Instead of a dead plain, the water surface lives and breathes in front of me. "

When a tidal wave enters the bay, which has a funnel-like shape in the plan, the shores of the bay compress it, as it were, causing the height of the tide to increase several times. So, in the Bay of Fundy off the eastern coast of North America, the tide height reaches 18 m. In Europe, the highest tides (up to 13.5 meters) are in Brittany near the city of Saint-Malo.

Very often the tidal wave enters the estuaries

Our planet is constantly in the gravitational field, which is created by the Moon and the Sun. This is the cause of a unique phenomenon, expressed in the ebb and flow of the earth. Let's try to figure out whether these processes affect environment and human activity.

The mechanism of the phenomenon "ebb and flow"

Such fluctuations in the water level can be shown in the following system:

• The water level gradually rises, reaching its highest point... This phenomenon is called full water.
• After a certain period of time, the water begins to subside. Scientists have defined this process as "ebb".
• For about six hours, the water continues to drain to its minimum point. This change was named in the form of the term "low water".

You can see some pattern if you observe the tide process in the same place for a month. The results of the analysis are interesting: daily low and high water changes its location. With this natural factor like the formation of a new moon and a full moon, the levels of the studied objects move away from each other.

Consequently, this makes the tide amplitude at its maximum twice a month. The appearance of the smallest amplitude also occurs periodically, when, after the characteristic influence of the Moon, the levels of small and full waters gradually approach each other.

The causes of ebb and flow on Earth

There are two factors that affect the formation of ebb and flow. It is necessary to carefully consider both objects that affect the change in the water space of the Earth.

The impact of lunar energy on the ebb and flow

The experimental results will show that the difference in their parameters is rather small. The thing is that the point on the Earth's surface closest to the Moon is subject to outside influence literally 6% more than the farthest. It is safe to say that this separation of forces pushes the Earth in the direction of the Moon-Earth trajectory.

Taking into account the fact that our planet constantly turns around its axis during the day, a double tidal wave passes twice along the perimeter of the created extension. This is accompanied by the creation of the so-called double "valleys", the height of which, in principle, does not exceed 2 meters in the oceans.

On the territory of the earth's land, such fluctuations reach a maximum of 40-43 centimeters, which in most cases remains unnoticed by the inhabitants of our planet.

All this leads to the fact that we do not feel the force of the ebb and flow either on land or in the water element. You can observe a similar phenomenon on a narrow strip of the coastline, because the waters of the ocean or sea, by inertia, sometimes gain impressive height.

From all that has been said, we can conclude that the ebb and flow are most associated with the Moon. This makes research in this area the most interesting and relevant.

Influence of solar activity on ebb and flow

It is a well-known fact that during the full moon and the growth of the moon, all three celestial bodies - the Earth, the Moon and the Sun - are located on one straight line. This leads to the folding of the lunar and solar tides.

During the period of direction from our planet to its satellite and the main star of the solar system, which differs from each other by 90 degrees, there is some influence of the Sun on the process under study. There is an increase in the level of low tide and a decrease in the level of high tide of the earth's waters.

All indications are that solar activity also affects the energy of the ebb and flow on the surface of our planet.

The main types of ebb and flow

1. Semi-daily changes in the surface of the water space... Such transformations consist in two full and the same amount of incomplete waters. The parameters of the alternating amplitudes are practically equal to each other and look like a sinusoidal curve. Most of all, they are localized in the waters of the Barents Sea, on the vast line of the coastal strip of the White Sea and on the territory of almost the entire Atlantic Ocean.
2. Daily fluctuations in water level... Their process consists in one full and incomplete water for a period calculated within a day. A similar phenomenon is observed in the Pacific Ocean region, and its formation is extremely rare. During the period of the passage of the Earth's satellite through the equatorial zone, the effect of standing water is possible. If the Moon tilts with the smallest index, small tides of an equatorial nature occur. At the highest numbers, the process of formation of tropical tides occurs, accompanied by the greatest power of water inflow.
3. Mixed tides... This concept includes the presence of semi-diurnal and diurnal tides of irregular configuration. The semi-diurnal changes in the level of the earth's water envelope, which have an irregular configuration, are similar in many ways to semi-diurnal tides. In altered diurnal tides, a tendency for diurnal fluctuations can be observed, depending on the degree of declination of the moon. The most prone to mixed tides are the waters of the Pacific Ocean.
4. Abnormal hot flashes... These rises and falls in water do not fit the description of some of the signs listed above. This anomaly is associated with the concept of "shallow water", which changes the cycle of rise and fall of the water level. The influence of this process is especially pronounced at river estuaries, where the tides are shorter in time than the ebb tides. You can observe a similar cataclysm in some parts of the English Channel and in the currents of the White Sea.

Earth's ebb and flow chart

• Designation of an area where it is important to know the data on the ebb and flow of the tide. It is worth remembering that even closely spaced objects will have different characteristics the phenomenon of interest.
• Finding necessary information using Internet resources. For more accurate information, you can visit the port of the region under study.
• Specifying the time needed for accurate data. This aspect depends on whether the information is needed for a specific day or the study schedule is more flexible.
• Working with the table in the mode of emerging needs. It will display all the tide information.

1. The columns at the top of the table indicate the days and dates of the alleged event. This item will allow you to find out the point of determining the time frame of the studied.
2. Under the line of temporary accounting there are numbers placed in two rows. In the format of the day, there is a decoding of the phases of the rising of the moon and the sun.
3. Below is a waveform chart. These indicators record the peaks (tides) and troughs (ebbs) of the waters of the study area.
4. After calculating the amplitude of the waves, the data of the arrival of celestial bodies are located, which affect the changes in the water shell of the Earth. This aspect will allow you to observe the activity of the Moon and the Sun.
5. On both sides of the table, you can see numbers with plus and minus indicators. This analysis is important for determining the level of rise or fall of water, measured in meters.

All these indicators cannot guarantee one hundred percent information, because nature itself dictates to us the parameters by which its structural changes occur.

The impact of ebb and flow on the environment and humans

There are many factors of the influence of ebb and flow on human life and the environment. Among them there are phenomenal discoveries that require careful study.

Killer waves: hypotheses and consequences of the phenomenon

The study of this object became possible with the help of radar satellites. These designs made it possible to record a dozen ultra-large amplitude waves over a period of a couple of weeks. The size of such a rise of the water block is about 25 meters, which indicates the grandeur of the phenomenon under study.

Killer waves directly affect human life, because over the past decades, such anomalies have carried huge vessels such as supertankers and container ships into the ocean depths. The nature of the formation of this stunning paradox is unknown: giant waves form instantly and just as quickly disappear.

There are many hypotheses regarding the reason for the formation of such a whim of nature, but the appearance of eddies (single waves due to the collision of two solitons) is possible with the interference of the activity of the Sun and the Moon. This issue is still becoming a reason for discussions among scientists specializing in this topic.

The effect of ebb and flow on organisms that inhabit the Earth

These include mollusks, which have perfectly adapted to the vibrations of the Earth's liquid shell. Oysters at the greatest tides begin to multiply actively, which indicates that they respond favorably to such changes in the structure of the water element.

But not all organisms respond so favorably to external changes. Many species of living things suffer from periodic fluctuations in water levels.

Although nature takes its toll and coordinates changes in the overall balance of the planet, biological substances adapt to the conditions presented to them by the activity of the Moon and the Sun.

The impact of ebb and flow on human life

Basically, this cyclical phenomenon only brings destruction and trouble. Modern technologies allow this negative factor to be directed in a positive direction.

An example of such innovative solutions are pools that trap such fluctuations in water balance. They must be built in a way that the project is cost-effective and practical.

To do this, it is necessary to create such pools of a rather significant size and volume. Power plants to contain the effect of the tidal force of the Earth's water resources is a new business, but quite promising.

Watch a video about the ebb and flow:

The oceans live by their own rules, which are harmoniously combined with the laws of the universe. For a long time, people noticed that they were actively moving, but they could not understand in any way what these fluctuations in sea level were connected with. Let's find out what is high tide, low tide?

Ebb and flow: mysteries of the ocean

The sailors knew very well that the ebb and flow is a daily occurrence. But the nature of these changes could not be understood either by ordinary residents or by scientists. As early as the fifth century BC, philosophers tried to describe and characterize how the oceans moved. seemed to be something fantastic and extraordinary. Even respected scientists considered the tides to be the breath of the planet. This version has existed for several millennia. Only at the end of the seventeenth century, the meaning of the word "tide" was associated with the movement of the moon. But it was not possible to explain this process from a scientific point of view. Hundreds of years later, scientists figured out this riddle and gave precise definition daily changes in water level. The science of oceanology, which appeared in the twentieth century, established that the tide is the rise and fall of the water level of the World Ocean in connection with the gravitational influence of the Moon.

Are the tides the same everywhere?

The influence of the moon on the earth's crust is not the same, so it cannot be said that the tides around the world are identical. In some parts of the world, daily sea level drops reach sixteen meters. And the inhabitants of the Black Sea coast practically do not notice the ebb and flow, since they are the smallest in the world.

Usually the change occurs twice a day - in the morning and in the evening. But in the South China Sea, the tide is the movement of water masses that occurs only once every twenty-four hours. Most of all, sea level changes are noticeable in straits or other narrow places. If you observe, then with the naked eye it will be noticeable how quickly the water leaves or comes. Sometimes it rises five meters in a few minutes.

As we have already found out, the change in sea level is caused by the impact on the earth's crust of its permanent satellite, the Moon. But how does this process take place? To understand what a tide is, it is necessary to understand in detail the interaction of all the planets in the solar system.

The moon and the earth are in constant dependence on each other. The Earth attracts its satellite, and that, in turn, seeks to attract our planet. This endless rivalry allows you to maintain the required distance between two space bodies. The moon and the earth move in their orbits, then moving away, then approaching each other.

At that moment, when the Moon comes closer to our planet, the earth's crust bends towards it. This causes the excitement of the water on the surface of the earth's crust, as if it seeks to rise higher. The receding of the earth's satellite causes a decline in the level of the World Ocean.

The interval of ebb and flow on Earth

Since the tide is a regular phenomenon, it must have its own certain interval of movement. Oceanologists were able to calculate exact time lunar days... It is customary to call this term the rotation of the Moon around our planet, it is slightly longer than the twenty-four hours we are accustomed to. Every day the ebb and flow of the tide is shifted by fifty minutes. This time interval is necessary for the wave to "catch up" with the Moon, which moves thirteen degrees over the earth's day.

Impact of ocean tides on rivers

We have already figured out what a tide is, but few people know about the influence of these oceanic fluctuations on our planet. Surprisingly, even rivers are affected by ocean tides, and sometimes the result of this intervention is incredibly frightening.

During heavy tides, a wave entering the mouth of a river meets a stream of fresh water. As a result of mixing water masses of different densities, a powerful shaft is formed, which begins to move at a tremendous speed against the flow of the river. This stream is called boron, and it is capable of destroying almost all living things on its way. A similar phenomenon washes away coastal settlements and the coastline in a matter of minutes. Bohr stops as suddenly as it started.

Scientists have recorded cases when a powerful forest turned rivers back or completely stopped them. It is not hard to imagine how disastrous these phenomenal tidal events have become for all the inhabitants of the river.

How do tides affect marine life?

Not surprisingly, tides have a huge impact on all organisms that live in the depths of the ocean. The hardest part is for small animals living in coastal zones... They are forced to constantly adapt to changing water levels. For many of them, tides are a way to change their habitat. During high tides, small crustaceans move closer to the coast and find food for themselves, the tidal wave pulls them deeper into the ocean.

Oceanologists have proven that many marine life are closely associated with tidal waves. For example, in some species of whales, their metabolism slows down during low tides. In other deep-sea inhabitants, reproductive activity depends on the wave height and its amplitude.

Most scientists believe that the disappearance of such phenomena as fluctuations in the level of the World Ocean will lead to the extinction of many living things. Indeed, in this case, they will lose their power source and will not be able to adjust their biological clock to a certain rhythm.

The Earth's Rotation Speed: Is the Influence of the Tides Great?

For many decades, scientists have been studying everything related to the term "tide". This is a process that brings more and more riddles every year. Many experts associate the speed of the Earth's rotation with the action of tidal waves. According to this theory, under the influence of tides are formed On their way, they constantly overcome the resistance of the earth's crust. As a result, almost imperceptibly for humans, the planet's rotation speed slows down.

By studying sea corals, oceanologists have found that a few billion years ago, the earth's day was twenty-two hours. In the future, the Earth's rotation will slow down even more, and at some point it will simply equal the amplitude of the lunar day. In this case, as scientists predict, the ebb and flow will simply disappear.

Human life activity and the amplitude of oscillations of the World Ocean

It is not surprising that a person is also susceptible to the action of hot flashes. After all, it is 80% liquid and cannot but respond to the influence of the moon. But man would not have been the crown of nature's creation if he had not learned to use practically everything for himself. natural phenomena.

The energy of the tidal wave is incredibly high, so they have been creating for many years various projects for the construction of power plants in areas with a large amplitude of movement of water masses. There are already several such power plants in Russia. The first was built in the White Sea and was an experimental version. The power of this station did not exceed eight hundred kilowatts. Now this figure seems ridiculous, and new power plants using the tidal wave are generating energy that powers many cities.

Scientists see these projects as the future of the Russian energy industry, because they allow them to treat nature more carefully and cooperate with it.

The ebb and flow are natural phenomena that not so long ago were completely unexplored. Each new discovery by oceanologists leads to even greater questions in this area. But perhaps someday scientists will be able to unravel all the secrets that the ocean tide presents to mankind every day.

Who wouldn't want to take a walk to the bottom of the sea? "It's impossible! you exclaim. - For this you need at least a caisson! " But don't you know that large areas of the seabed open up for observation twice a day? True, woe to those who decide to stay at this "exhibition" beyond the established time! The seabed opens at low tide. - this is a change of high and low water.

This is one of the mysteries of nature. Many naturalists tried to solve it: Kepler who discovered the law of planetary motion, Newton who established the basic laws of motion, the French scientist Laplace, who studied the emergence of celestial bodies. They all wanted to penetrate the secrets of the life of the oceans.

The wind creates waves on the sea. But the wind is too weak to control the ebb and flow. Even a storm can only help with the tide. What gigantic forces are doing such hard work?

The influence of the moon on ebb and flow

Three giants are fighting for the world's oceans: The sun, the moon and the earth itself... The sun is stronger than all, but it is too far from us to be the winner. The movement of water masses on Earth is mainly controlled by the Moon. Located at a distance of 384,000 kilometers from Earth, it regulates the "pulse" of the oceans. Like a huge magnet, the Moon pulls masses of water up several meters while the Earth rotates on its axis.

Although the difference between the heights of ebb and flow is on average no more than 4 meters, the work that the moon is doing is enormous. It is equal to 11 trillion horsepower. If this number is written in numbers alone, then it will have 18 zeros and look like this: 11,000,000,000,000,000,000. You cannot collect such a number of horses, even if you drive herds from all "ends" of the globe.

Ebb and flow - sources of energy

After the sun ebb and flow- The biggest energy sources... They could give electricity all over the world. Since time immemorial, man has tried to make the moon serve him. In China and elsewhere, tidal waters have been driving millstones for a long time.

In 1913, the first "lunar" power station was put into operation in the North Sea near Husum. In England, France, the United States, and especially in Argentina, feeling a lack of fuel, many bold projects for the construction of tidal stations have been created. However, Soviet engineers went farthest, who created a project for the construction of a dam 100 kilometers long and 15 meters high in the Mezen Bay of the White Sea.

At high tide, a reservoir with a capacity of 2 thousand square kilometers is formed behind the dam. Two thousand turbine generators will provide 36 billion kilowatt-hours. This amount of energy was produced in 1929 by France, Italy and Switzerland combined. A kilowatt-hour of this energy will cost about one penny. Unfortunately, the "pulse" ebb and flow of the sea beats with unequal strength, like the pulse of a person. The tides do not provide a constant, uniform flow of water, and this makes the project difficult.

The tide is strongest when the Sun and Moon pull masses of water in the same direction. High tides when the water level rises up to 20 meters, are at full and young moon... They are called "syzygy". In the first and last quarter of the month when the moon is at right angles to the sun, tides are lowest and are called "quadrature".

The ebb and flow of the sea is very great importance for navigation, and therefore their offensive calculated in advance... This calculation is so difficult that it takes many weeks to compile the annual tide calendar. But the ingenious mind of man has created a calculating machine, the "electronic brain" of which makes predictions of tides in two days. The tide calendar shows that tidal waves travel across the globe at regular intervals. From the sea shores, they rise into rivers.

© Vladimir Kalanov,
"Knowledge is power".

The phenomenon of tides at sea has been noticed since ancient times. Herodotus wrote about tides as early as the 5th century BC. For a long time people could not understand the nature of the tides. Various fantastic assumptions have been made, such as that the Earth breathes. Even the famous scientist (1571-1630), who discovered the laws of planetary motion, considered the ebb and flow as a result ... of the breathing of the planet Earth.

The French mathematician and philosopher (1596-1650) was the first among European scientists to point out the connection between tides and, but did not understand what this connection was. Therefore, he gave such a far from the truth explanation of the phenomenon of tide: the Moon, revolving around the Earth, presses on the water, forcing it to go down.

Gradually, scientists figured out this, I must say, difficult problem, and it was found that tides are a consequence of the influence of the gravitational forces of the Moon and (to a lesser extent) the Sun on the surface of the ocean.

In oceanology it is given following definition: rhythmic rises and falls of waters, as well as their accompanying currents, are called ebb and flow.

High and low tides occur not only in the ocean, but also in the atmosphere and the earth's crust. The uplift of the earth's crust is very insignificant, so they can only be determined special devices... Another thing is the water surface. Particles of water move, and, receiving acceleration from the moon, approach it incomparably more than the earth's solid. Therefore, on the side facing the moon, the water rises upward, forming a bend, a kind of water bump on the surface of the ocean. As the Earth rotates on its axis, this water bump moves along the surface of the ocean following.

In theory, even distant stars are involved in the formation of tides. But this remains a purely theoretical premise, since the effect of the stars is negligible and can be neglected. More precisely, it is even impossible to neglect it, since there is nothing to neglect. The influence of the Sun on the surface of the ocean is 3-4 times weaker than the influence of the Moon due to the great distance of the star. Powerful lunar tides mask the Sun's gravitational pull, and so there are no solar tides as such.

The extreme position of the water level at the end of the tide is called full of water, and at the end of low tide - low water.

Two photographs taken from the same point at moments of low and high water,
give an idea of ​​tidal level fluctuations.

If we start observing the tide at the time of high water, then we will see that after 6 hours the lowest water level will come. After that, the tide will begin again, which will also continue for 6 hours until the highest level is reached. The next high tide will come 24 hours after the start of our observation.

But this will only happen in the case of ideal, theoretical conditions. In reality, during the day there is one full and one low water - and then the tide is called daily. Or it can happen in two tidal cycles. In this case, we are talking about a semi-daily tide.

The period of daily tide does not last 24 hours, but 50 minutes longer. Accordingly, the semi-daily tide lasts 12 hours and 25 minutes.

The world's oceans are dominated by semi-diurnal tides. This is declared by the rotation of the Earth around its axis. The tide, like a huge gentle wave length of many hundreds of kilometers, spreads over the entire surface of the World Ocean. The period of occurrence of such a wave fluctuates in each place of the ocean from half a day to a day. On the basis of the frequency of the onset of tides, they are distinguished as daily and semi-daily.

During a complete revolution of the Earth around its axis, the Moon moves about 13 degrees across the sky. To "catch up" with the Moon, the tidal wave just takes 50 minutes. This means that the time of arrival of full water in the same place in the ocean is constantly shifting relative to the time of day. So, if today there was full water at noon, then tomorrow it will be at 12 hours 50 minutes, and the day after tomorrow - at 13 hours 40 minutes.

In the open ocean, where the tidal wave does not meet resistance from the continents, islands, uneven bottom and coastline, there are mostly regular semi-diurnal tides. Tidal waves in the open ocean are invisible, where their height does not exceed one meter.

In full force, the tide manifests itself on the open coast of the ocean, where for tens and hundreds of miles, no islands or sharp bends of the coastline are visible.

When the Sun and the Moon are located on the same line on one side of the Earth, the force of attraction of both luminaries adds up, as it were. This happens twice during a lunar month - on a new moon or a full moon. This position of the luminaries is called syzygy, and the tide that comes on these days is called. Syzygy tides are the highest and most powerful tides. In contrast, the lowest tides are called.

It should be noted that the level of syzygy tides in the same place is not always the same. The reason is the same: the movement of the Moon around - the Earth and the Earth - around the Sun. Let's not forget that the orbit of the Moon around the Earth is not a circle, but an ellipse, which creates a rather tangible difference between the perigee and apogee of the Moon - 42 thousand km. If during the syzygy the Moon is in perigee, that is, at the smallest distance from the Earth, then this will cause a high tidal wave. Well, if during the same period the Earth, moving in its elliptical orbit around the Sun, is at the smallest distance from it (and also coincidences occasionally occur), then the ebb and flow will reach the maximum value.

Here are some examples showing the maximum heights that ocean tides reach at specific locations in the world (in meters):

Water rises at different rates during high tide. The nature of the tide is highly dependent on the angle of inclination of the seabed. At steep banks, the water rises slowly at first - 8-10 millimeters per minute. Then the tide speed increases, becoming the highest towards the half-water position. Then it slows down to the position of the upper tide limit. The dynamics of the ebb tide is similar to the dynamics of the tide. But the tide looks quite different on wide beaches. Here the water level rises very quickly and is sometimes accompanied by a high tidal wave that rushes rapidly along the shallows. Those who gape on such beaches shouldn't expect anything good in these cases. The sea element does not know how to joke.

In the inland seas, fenced off from the rest of the ocean by narrow and shallow winding straits or clusters of small islands, tides come with barely noticeable amplitudes. We see this in the example of the Baltic Sea, which is reliably closed from the tides by shallow Danish straits. The theoretical height of the tide in the Baltic Sea is 10 centimeters. But these tides are invisible to the eye, they are hidden by fluctuations in the water level from the wind or from changes in atmospheric pressure.

It is known that in St. Petersburg there are frequent floods, sometimes very strong. Let us remember how vividly and truthfully he conveyed the drama of the strongest flood of 1824 in the poem “ Bronze Horseman"The great Russian poet A.S. Pushkin. Fortunately, floods of such force in St. Petersburg have nothing to do with the tides. These floods are caused by cyclone winds, which significantly raise the water level by 4–5 meters in the eastern part of the Gulf of Finland and in the Neva.

The ocean tides are even less affected by the inland seas of the Black and Azov, as well as the Aegean and Mediterranean. In the Sea of ​​Azov, connected to the Black Sea by the narrow Kerch Strait, the amplitude of the tides is close to zero. In the Black Sea, fluctuations in water level under the influence of tides do not even reach 10 centimeters.

Conversely, in bays and narrow bays that have free communication with the ocean, the tides reach significant levels. Freely entering the bay, tidal masses rush forward, and, finding no way out among the narrowing shores, rise up and flood the land over a large area.

During ocean tides, a dangerous phenomenon is observed in the estuaries of some rivers, called boron... The stream of sea water, entering the riverbed and meeting with the river stream, forms a powerful foamy shaft, rising up as a wall and rapidly moving against the stream of the river. On its way, the forest erodes the banks and can destroy and sink any ship if it is in the channel of the river.

On the Amazon, the greatest river in South America, a powerful tidal wave 5-6 meters high travels at a speed of 40-45 km / h at a distance of up to one and a half thousand kilometers from the mouth.

Sometimes tidal waves stop the flow of rivers and even turn it in the opposite direction.

On the territory of Russia, small-in-height boron is experienced by rivers flowing into the Mezen Bay of the White Sea.

In order to use the energy of tides in some countries, including Russia, tidal power plants have been built. The first tidal power plant, built in the Kislogubskaya Bay of the White Sea, had a capacity of only 800 kilowatts. Subsequently, TPPs were designed with a capacity of tens and hundreds of thousands of kilowatts. This means that hot flashes begin to work for the benefit of the person.

And last, but globally important, about tides. Tidal currents meet resistance from continents, islands and the seabed. Some scientists believe that as a result of the friction of water masses against these obstacles, the rotation of the Earth around its axis slows down. At first glance, this slowdown is quite insignificant. Calculations have shown that over the entire time of our era, that is, over 2000 years, the day on Earth became 0.035 seconds longer. But what was the calculation based on?

It turns out that there is evidence, albeit indirect, that the rotation of our planet is slowing down. Studying the extinct corals of the Devonian period, the English scientist D. Wells found that the number of diurnal growth rings is 400 times more than the annual ones. In astronomy, the theory of stability of planetary movements is recognized, according to which the length of the year remains practically unchanged.

It turns out that in the Devonian period, that is, 380 million years ago, a year consisted of 400 days. Consequently, the day then had a duration of 21 hours 42 minutes.

If D. Wells was not mistaken in calculating the daily rings of ancient corals, and if the rest of the calculations are correct, then everything goes to the fact that some 12-13 billion years will not pass, as the earth's day will become equal in length to the lunar month. And then what? Then our Earth will be constantly facing one side of the Moon, as is currently the case with the Moon in relation to the Earth. The rise in water will stabilize on one side of the Earth, the tides will cease to exist, and the solar tides are too weak to be felt.

We provide an opportunity for our readers to independently assess this rather exotic hypothesis.

© Vladimir Kalanov,
"Knowledge is power"