Formation of sea waves. Why are there waves on the sea? How sea waves are formed

The surface of the seas and oceans is rarely calm: it is usually covered with waves, and the surf continuously beats against the shores.

An amazing sight: a massive cargo ship, which is played by giant storm waves in the open ocean, appears to be no more than a nutshell. Disaster films are replete with similar images - a wave as high as a ten-story building.

Wave oscillations of the sea surface occur during a storm, when a long gusty wind combined with changes in atmospheric pressure forms a complex chaotic wave field.

Running waves, boiling surf foam

Moving away from the cyclone that caused the storm, you can observe how the wave pattern is transformed, how the waves become more even and orderly rows moving one after another in the same direction. These waves are called swell. The height of such waves (that is, the difference in levels between the highest and lowest points of the wave) and their length (the distance between two adjacent peaks), as well as the speed of their propagation, are quite constant. Two crests can be separated by a distance of up to 300 m, and the height of such waves can reach 25 m. Wave vibrations from such waves propagate to a depth of 150 m.

From the area of ​​formation, swell waves travel very far, even in complete calm. For example, cyclones passing off the coast of Newfoundland cause waves that in three days reach the Bay of Biscay off the western coast of France - almost 3000 km from where they formed.

When approaching the shore, as the depth decreases, these waves change their appearance. When wave vibrations reach the bottom, the movement of the waves slows down, they begin to deform, which ends with the collapse of the crests. Surfers look forward to these waves. They are especially spectacular in areas where the seabed drops sharply near the coast, for example in the Gulf of Guinea in western Africa. This place is very popular among surfers all over the world.

Tides: global waves

Tides are a phenomenon of a completely different nature. These are periodic fluctuations in sea level, clearly visible off the coast and repeating approximately every 12.5 hours. They are caused by the gravitational interaction of ocean waters mainly with the Moon. The period of tides is determined by the ratio of the periods of the daily rotation of the Earth around its axis and the rotation of the Moon around the Earth. The Sun also participates in the formation of tides, but to a lesser extent than the Moon. Despite the superiority in mass. The sun is too far from the Earth.

The total magnitude of the tides thus depends on the relative positions of the Earth, Moon and Sun, which changes throughout the month. When they are on the same line (which happens during the full moon and new moon), the tides reach their maximum values. The highest tides are observed in the Bay of Fundy on the coast of Canada: the difference between the maximum and minimum sea level positions here is about 19.6 m.

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Essay by Y. LESNY

If we could ride the Welsh “time machine”, rush on it into the foggy distance of the past and from there look at our globe, we would not recognize it. Millions of years ago, the continents not only had completely different outlines, but the very surface of these continents had a completely different appearance: different, alien landscapes covered them, different plants grew and different animals were found. Man with his cities, plowed fields and roads did not exist then... Only one thing remained unchanged throughout all geological periods: this view of the sea. Millions of years ago, the same waves rolled over it that plow it now. The sight of the rippling water surface is the most ancient landscape we know on earth. And even today it is the most common: after all, two-thirds of the entire surface of our planet is covered with water!

But can we say that this ancient and widespread landscape is familiar to us better than all others? Hardly. We are involuntarily drawn to the harsh beauty of the stormy sea, it inspires poets and artists, but still we know little about the waves of the sea. Even the very type of this wave-like movement most people imagine is completely wrong.

In fact, most people think that waves seem to glide over the surface of the sea, moving along it, like water in a river bed. But this is not true: in a rough sea, only the form of movement moves, while the waves themselves oscillate only up and down. Have you ever seen a piece of wood, a boat, or any floating object being moved by a rough sea? Please note that the fast-moving waves do not carry this object with them at all, but only gently swing it up and down. The sea is agitated in exactly the same way as “a yellowing field is agitated”: the ears of corn do not change their place on the field, each ear of grain is only slightly pumped forward and then becomes straight again - and meanwhile you see waves running across the field one after another. It is the form of movement that runs, not the ears themselves.

The proverb “worldly rumor is like a sea wave” surprisingly clearly illustrates this peculiar kind of movement. For some news to spread throughout the city, it is not necessary for people to run from one end of the city to the other: word of mouth is passed on from mouth to mouth.

In this way, sea waves differ from those sand waves with which the wind plows deserts and coastal areas: here the undulating hills of sand actually, by themselves, move, and only their shape does not move, as on the sea.

That is why the waves of the sea run with such enormous speed, often overtaking our “fast” trains: wave speeds of 5...6 fathoms per second, or 40 versts per hour, are not uncommon. If it were not the form of movement that moved, but the water masses themselves, such a speed would be impossible.

But we have not yet said anything about the reason that generates the waves. This reason, as is known, is the wind, i.e. air flow. By striking the water, the air current bends its surface; a depression is formed, but the next moment the descending water particles are forcefully pushed upward, so that a rise is formed in place of the depression. This elevation, falling down under the influence of gravity, is again replaced by a valley, etc. Each particle of water in a rough sea moves only up and down, but the excitement, starting at one point, is transmitted to neighboring particles, spreading further and further, covering a huge area. The movement of an undulating field illustrates this phenomenon quite well.

But the wind is not the only reason for sea disturbances. Another, rarer reason is earthquakes that occur near the coast. Such waves are not high, but very long and travel with extraordinary speed, sometimes over 600 versts per hour! But this kind of waves are observed much less frequently than waves originating from the wind. In what follows we will primarily refer to these latter ones.

How big are the waves? We often hear about the colossal size of sea waves, about water mountains the height of a multi-story building. Accurate measurements destroyed this legend about the incredible height of the waves, and it is curious that the more accurate the measurements were, the lower the waves turned out to be. In the open sea, waves rarely reach more than 6 fathoms in height; This is the maximum height, but usually waves are not higher than 3 fathoms, so a 5-fathom wave should be considered as an exception.

But if so, then where, the reader will ask, did these stories about mountain-like sea waves come from, stories that one sometimes hears from the most conscientious eyewitnesses? Here the matter lies in a curious illusion of vision. Waves on the open sea must be observed, of course, from the deck of ships, which during waves does not remain horizontal, but bends in all directions. When the deck, during pitching, tilts the passenger towards the sea, he sees huge water waves in front of him - and involuntarily overestimates their height, since he calculates it not from the horizontal surface, but from the inclined deck. In other words, the passenger mentally measures not the vertical rise of the wave, but the length of its slope. As a result of this optical illusion, which, of course, is not recognized by the passenger, the waves appear so huge to him.

It is interesting to note that wave heights are not the same in all seas. The deeper the sea, the more extensive its surface, the fewer islands and shoals on it that interfere with the unhindered movement of water masses and wind - the larger the waves. In this case, the salinity of the water, or rather its density, also plays a certain role. Salt water is heavier than fresh water and is less susceptible to wind forces than fresh water; That’s why the saltier the water, the lower the waves. That is why, with equal areas, lakes are more stormy than sea bays, separated from the sea by rocks and sand banks. But if the areas of the water basins are not equal, then, as we have already mentioned, their waves will not be the same. In our Caspian Sea the waves are much smaller than in the vast Mediterranean Sea, and in the latter they are again much smaller than in the Atlantic Ocean. In turn, Atlantic waves never reach the dimensions that frighten swimmers of the Antarctic Ocean, which freely spreads over the vast expanse of the southern hemisphere.

So far we have talked about the height of the waves and have not yet said anything about their length, i.e. about the distance between the crests (or between the valleys) of two adjacent waves. The higher the waves, the greater their width, and there is a fairly simple relationship between these two quantities; namely, the width is approximately 30...40 times greater than the height. Waves of three fathoms height reach 100 fathoms in length, and 5...6 fathoms, i.e. the highest waves can reach a length of up to half a mile.

We may be interested in another question here: how deep underwater does the disturbance spread? This is not an idle question - it has important practical significance for scuba diving, when laying sea cables, etc. Until recently, it was accepted that the depth of wave propagation was equal to 300 times the wave height. It follows, for example, that when waves of 3 fathoms are moving on the surface of the sea, then the echoes of this excitement are felt at a depth of 3x300 = 900 fathoms, i.e. almost two miles. It is now doubted that the disturbance could extend to such depths. Direct measurements have established, however, that at a depth of 100 fathoms it is still felt, so the serene sailing of Jules Vernov’s Nautilus shallowly below the level of the stormy sea belongs to the realm of fantasy.

Many people are not even aware of the enormous significance that sea waves have in nature. For a person who entrusts his ships to the sea, excitement is an undesirable phenomenon: we would give a lot so that the boundless expanse of the ocean would always be calm and motionless. But those numerous living beings who live in its bottomless depths have a completely different attitude towards this. Unrest increases the surface of contact between water and air, and thus contributes to the penetration of oxygen into the thickness of water masses, without which life is impossible. This is the important role that excitement plays in saving nature! Breaking and burying our ships, storms bring a life-giving elixir into the boundless underwater world.

However, the time is not far off when man will also benefit from the waves of the sea, put a yoke on them and force them to set their mechanisms in motion.

Rice. 1.

It would seem strange to talk about the enslavement of sea waves by man, but even now mechanisms are being built that are set in motion by nothing other than the waves of the sea. As an example, we will describe here the recently invented machine of the American engineer Ransom. The purpose of the machine is to use the energy of sea waves to condense air, which, as is known, can drive all kinds of mechanisms. The design of Ransom's machine is not complicated. Through the block A a rope is thrown, from which an empty iron box is hung B and cargo C. Wave lifting a floating box IN, thereby rotating the block A and a gear wheel connected to it. This latter moves the pistons of the cylinders D. When the wave subsides, the box also goes down with it B, and the gear moves in the opposite direction. The mechanism is designed in such a way that with every movement of the gear, the pistons in the cylinders move alternately forward or backward, all the time pumping air into the cylinders D. Compressed air flows through the tube E into the tank F, where it accumulates. Thus, there is always a free source of energy in the reservoir in the form of compressed air; All that remains is to put it to work.

There are other types of such gift engines; for now they do not yet have practical significance, but in the near future the industrial use of wave energy will undoubtedly be put on a wider scale. And then man will not only conquer the sea, but also make its rebellious waves his obedient slaves.

A source of information:

"Nature and People".
Illustrated magazine of science, art and literature. 1912, No. 2

The waves that we are used to seeing on the surface of the sea are formed mainly under the influence of wind. However, waves can also arise for other reasons, then they are called;

Tidal, formed under the influence of the tidal forces of the Moon and the Sun;

Baric pressure, which occurs during sudden changes in atmospheric pressure;

Seismic (tsunami) formed as a result of an earthquake or volcanic eruption;

Ship problems that arise when the ship is moving.

Wind waves are predominant on the surface of seas and oceans. Tidal, seismic, pressure and ship waves do not have a significant effect on the navigation of ships in the open ocean, so we will not dwell on their description. Wind waves are one of the main hydrometeorological factors that determine the safety and economic efficiency of navigation, since the wave, running onto the ship, hits it, rocks it, hits the side, floods the decks and superstructures, and reduces the speed. The motion creates dangerous lists, makes it difficult to determine the position of the vessel and greatly exhausts the crew. In addition to the loss of speed, waves cause the vessel to yaw and deviate from the given course, and to maintain it, constant shifting of the rudder is required.

Wind waves are the process of formation, development and propagation of wind-induced waves on the sea surface. Wind waves have two main features. The first feature is irregularity: disorder in the sizes and shapes of waves. One wave does not repeat another; a large one may be followed by a small one, or perhaps an even larger one; Each individual wave continuously changes its shape. Wave crests move not only in the direction of the wind, but also in other directions. Such a complex structure of the disturbed sea surface is explained by the vortex, turbulent nature of the wind that forms waves. The second feature of waves is the rapid variability of its elements in time and space and is also associated with the wind. However, the size of the waves depends not only on the wind speed; the duration of its action, the area and configuration of the water surface are of significant importance. From a practical point of view, there is no need to know the elements of each individual wave or each wave vibration. Therefore, the study of waves ultimately comes down to identifying statistical patterns that are numerically expressed by the dependencies between wave elements and the factors that determine them.

3.1.1. Wave elements

Each wave is characterized by certain elements,

The common elements for waves are (Fig. 25):

Apex - the highest point of the wave crest;

The bottom is the lowest point of the wave trough;

Height (h) - exceeding the top of the wave;

Length (L) is the horizontal distance between the tops of two adjacent ridges on a wave profile drawn in the general direction of wave propagation;

Period (t) - the time interval between the passage of two adjacent wave peaks through a fixed vertical; in other words, it is the period of time during which the wave travels a distance equal to its length;

Slope (e) is the ratio of the height of a given wave to its length. The steepness of the wave at different points of the wave profile is different. The average wave steepness is determined by the ratio:

Rice. 25. Basic elements of waves.

For practice, the greatest slope is important, which is approximately equal to the ratio of the wave height h to its half-length λ/2

- wave speed c - the speed of movement of the wave crest in the direction of its propagation, determined over a short time interval of the order of the wave period;

Wave front is a line on the plan of a rough surface, passing along the vertices of the crest of a given wave, which are determined by a set of wave profiles drawn parallel to the general direction of wave propagation.

For navigation, wave elements such as height, period, length, steepness and general direction of wave movement are of greatest importance. All of them depend on the parameters of the wind flow (wind speed and direction), its length (acceleration) over the sea and the duration of its action.

Depending on the conditions of formation and propagation, wind waves can be divided into four types.

Wind - a system of waves that, at the moment of observation, is under the influence of the wind by which it is caused. The directions of propagation of wind waves and wind in deep water usually coincide or differ by no more than four points (45°).

Wind waves are characterized by the fact that their leeward slope is steeper than the windward one, so the tops of the crests usually collapse, forming foam, or are even torn off by strong winds. When waves enter shallow water and approach the shore, the directions of wave and wind propagation can differ by more than 45°.

Swell - wind-induced waves that propagate in the wave-forming area after the wind weakens and/or changes its direction, or wind-induced waves that come from the wave-forming area to another area where the wind is blowing at a different speed and/or a different direction. A special case of swell that propagates in the absence of wind is called a dead swell.

Mixed - waves formed as a result of the interaction of wind waves and swell.

Transformation of wind waves - changes in the structure of wind waves with changes in depth. In this case, the shape of the waves is distorted, they become steeper and shorter, and at a shallow depth, not exceeding the height of the wave, the crests of the latter overturn and the waves are destroyed.

In their appearance, wind waves are characterized by different shapes.

Ripple is the initial form of wind wave development that occurs under the influence of a weak wind; The crests of the waves resemble scales when they ripple.

Three-dimensional waves are a set of waves whose average crest length is several times greater than the average wavelength.

Regular waves are waves in which the shape and elements of all waves are the same.

Crowd is a chaotic disturbance that arises as a result of the interaction of waves traveling in different directions.

Waves breaking over banks, reefs or rocks are called breakers. Waves crashing in the coastal area are called surf. Near steep shores and near port facilities, the surf has the form of a reverse surge.

Waves on the surface of the sea are divided into free, when the force that caused them ceases to act and the waves move freely, and forced, when the force that caused the formation of the waves does not stop.

Based on the variability of wave elements over time, they are divided into steady waves, i.e., wind waves, in which the statistical characteristics of waves do not change over time, and developing or attenuating waves, which change their elements over time.

According to their shape, waves are divided into two-dimensional - a set of waves whose average crest length is many times greater than the average wavelength, three-dimensional - a set of waves whose average crest length is several times greater than the wave length, and solitary, having only a dome-shaped crest without a sole.

Depending on the ratio of the wavelength to the depth of the sea, waves are divided into short, the length of which is significantly less than the depth of the sea, and long, the length of which is greater than the depth of the sea.

According to the nature of the movement of the waveform, they can be translational, in which there is visible movement of the waveform, and standing - having no movement. Based on how the waves are located, they are divided into surface and internal. Internal waves are formed at one or another depth at the interface between layers of water of different densities.

3.1.2. Methods for calculating wave elements

When studying sea waves, certain theoretical principles are used to explain certain aspects of this phenomenon. The general laws of the structure of waves and the nature of the movement of their individual particles are considered by the trochoidal theory of waves. According to this theory, individual water particles in surface waves move in closed ellipsoidal orbits, making a full revolution in a time equal to the wave period t.

The rotational motion of successively located water particles, shifted by a phase angle at the initial moment of movement, creates the appearance of translational motion: individual particles move in closed orbits, while the wave profile moves translationally in the direction of the wind. The trochoidal wave theory made it possible to mathematically substantiate the structure of individual waves and relate their elements to each other. Formulas were obtained that made it possible to calculate individual wave elements

where g is the acceleration of gravity, the wavelength K, the speed of its propagation C and the period t are related to each other by the dependence K = Cx.

It should be noted that the trochoidal wave theory is valid only for regular two-dimensional waves, which are observed in the case of free wind waves - swell. In three-dimensional wind waves, the orbital paths of particles are not closed circular orbits, since under the influence of wind, horizontal transfer of water occurs on the sea surface in the direction of wave propagation.

The trochoidal theory of sea waves does not reveal the process of their development and attenuation, as well as the mechanism of energy transfer from wind to wave. Meanwhile, solving precisely these issues is necessary in order to obtain reliable dependencies for calculating the elements of wind waves.

Therefore, the development of the theory of sea waves took the path of developing theoretical and empirical connections between wind and waves, taking into account the diversity of real sea wind waves and the non-stationary nature of the phenomenon, i.e., taking into account their development and attenuation.

In general, formulas for calculating wind wave elements can be expressed as a function of several variables

H, t, L,C=f(W , D t, H),

Where W is wind speed; D - acceleration, t - duration of wind action; H - depth of the sea.

For shallow sea areas, the dependences can be used to calculate wave height and length

Coefficients a and z are variable and depend on the depth of the sea

A = 0.0151H 0.342; z = 0.104H 0.573 .

For open sea areas, the elements of waves, the probability of heights of which is 5%, and the average wavelengths are calculated according to the dependencies:

H = 0.45 W 0.56 D 0.54 A,

L = 0.3lW 0.66 D 0.64 A.

Coefficient A is calculated using the formula

For open ocean areas, wave elements are calculated using the following formulas:

where e is the steepness of the wave at low accelerations, D PR is the maximum acceleration, km. The maximum height of storm waves can be calculated using the formula

where hmax is the maximum wave height, m, D is the acceleration length, miles.

At the State Oceanographic Institute, based on the spectral statistical theory of waves, graphical connections were obtained between wave elements and wind speed, duration of its action and acceleration length. These dependencies should be considered the most reliable, giving acceptable results, on the basis of which nomograms for calculating wave heights were constructed at the Hydrometeorological Center of the USSR (V.S. Krasyuk). The nomogram (Fig. 26) is divided into four quadrants (I-IV) and consists of a series of graphs arranged in a certain sequence.

In quadrant I (counting from the lower right corner) of the nomogram, a degree grid is given, each division of which (horizontally) corresponds to 1° of the meridian at a given latitude (from 70 to 20° N) for maps at a scale of 1:15 000000 polar stereographic projections. The degree grid is necessary to convert the distance between the isobars n and the radius of curvature of the isobars R, measured on maps of a different scale, to a scale of 1:15 000000. In this case, we determine the distance between the isobars n and the radius of curvature of the isobars R in meridian degrees at a given latitude. The radius of curvature of isobars R is the radius of the circle with which the section of the isobar passing through or near the point for which the calculation is being carried out has the greatest contact. It is determined using a meter by selecting it in such a way that an arc drawn from the found center coincides with a given section of the isobar. Then, on a degree grid, we plot the measured values ​​at a given latitude, expressed in degrees of the meridian, and using a compass we determine the radius of curvature of the isobars and the distance between the isobars, corresponding to a scale of 1:15,000,000.

Quadrant II of the nomogram shows curves expressing the dependence of wind speed on the pressure gradient and geographic latitude of the place (each curve corresponds to a certain latitude - from 70 to 20° N). To transition from the calculated gradient wind to the wind blowing near the sea surface (at an altitude of 10 m), a correction was derived that takes into account the stratification of the surface layer of the atmosphere. When calculating for the cold part of the year (stable stratification t w 2°C), the coefficient is 0.6.

Rice. 26. Nomogram for calculating wave elements and wind speed from surface pressure field maps, where isobars are drawn at intervals of 5 mbar (a) and 8 mbar (b). 1 - winter, 2 - summer.

In quadrant III, the influence of isobar curvature on the geostrophic wind speed is taken into account. Curves corresponding to different values ​​of the radius of curvature (1, 2, 5, etc.) are given by solid (winter) and dashed (summer) lines. The sign oo means that the isobars are straight. Typically, when the radius of curvature exceeds 15°, it is not necessary to take curvature into account in calculations. Along the abscissa axis separating keys III and IV, the wind speed W for a given point is determined.

In quadrant IV there are curves that make it possible to determine the height of the so-called significant waves (h 3H), which have a probability of 12.5%, based on wind speed, acceleration or duration of wind action.

If it is possible, when determining wave height, to use not only data on wind speed, but also on the acceleration and duration of the wind, the calculation is performed using the acceleration and duration of the wind (in hours). To do this, from quadrant III of the nomogram we lower the perpendicular not to the acceleration curve, but to the wind duration curve (6 or 12 hours). From the results obtained (in terms of acceleration and duration), the smaller value of the wave height is taken.

Calculation using the proposed nomogram can be made only for areas of the “deep sea”, i.e. for areas where the sea depth is not less than half the wavelength. When acceleration exceeds 500 km or wind duration exceeds 12 hours, the dependence of wave heights on wind corresponding to ocean conditions is used (thickened curve in quadrant IV).

Thus, to determine the height of the waves at a given point, it is necessary to perform the following operations:

A) find the radius of curvature of the isobar R passing through a given point or near it (using a compass by selection). The radius of curvature of isobars is determined only in the case of cyclonic curvature (in cyclones and troughs) and is expressed in meridian degrees;

B) determine the pressure difference n by measuring the distance between adjacent isobars in the area of ​​the selected point;

C) using the found values ​​of R and n, depending on the time of year, we find the wind speed W;

D) knowing the wind speed W and acceleration D or the duration of the wind (6 or 12 hours), we find the height of significant waves (h 3H).

Acceleration is found as follows. From each point for which the wave height is calculated, a streamline is drawn in the direction against the wind until its direction changes relative to the initial one by an angle of 45° or reaches the shore or the ice edge. Approximately this will be the acceleration or path of the wind, along which waves should be formed, arriving at a given point.

The duration of wind action is defined as the time during which the wind direction remains unchanged or deviates from the original by no more than ±22.5°.

According to the nomogram in Fig. 26a, you can determine the wave height from a map of the surface pressure field, on which isobars are drawn through 5 mbar. If the isobars are drawn through 8 mbar, then the nomogram shown in Fig. 26 b.

The wave period and length can be calculated from wind speed and wave height data. An approximate calculation of the wave period can be made using the graph (Fig. 27), which shows the relationship between the periods and the height of wind waves at different wind speeds (W). The wave length is determined by its period and sea depth at a given point according to the graph (Fig. 28).

The wind itself can be seen on weather forecast maps: these are low pressure zones. The greater their concentration, the stronger the wind will be. Small (capillary) waves initially move in the direction in which the wind is blowing.

The stronger and longer the wind blows, the greater its impact on the surface of the water. Over time, the waves begin to increase in size.

Wind has a greater effect on small waves than on calm water surfaces.

The size of the wave depends on the speed of the wind that forms it. A wind blowing at some constant speed will be able to generate a wave of comparable size. And once the wave reaches the size that the wind can push into it, it becomes “fully formed.”

The generated waves have different speeds and wave periods. (More details in the article) Long-period waves travel faster and travel longer distances than their slower counterparts. As they move away from the wind source (propagation), the waves form swell lines that inevitably roll onto the shore. Most likely, you are familiar with the concept of set waves!

Are waves that are no longer affected by the wind called ground swells? This is exactly what surfers are after!

What affects the size of a swell?

There are three main factors that influence the size of waves on the open sea.
Wind speed– The larger it is, the larger the wave will be.
Wind duration– similar to the previous one.
Fetch(wind coverage area) – again, the larger the coverage area, the larger the wave is formed.

As soon as the wind stops affecting them, the waves begin to lose their energy. They will move until the protrusions of the seabed or other obstacles in their path (a large island, for example) absorb all the energy.

There are several factors that influence the size of a wave at a particular location. Among them:

Swell direction– will it allow the swell to get to the place we need?
ocean floor– A swell moving from the depths of the ocean onto an underwater ridge of rocks forms large waves with barrels inside. A shallow ledge opposite will slow down the waves and cause them to lose energy.
Tidal cycle– some sports completely depend on it.

Find out how the best waves are made.

Initially, a wave appears due to the wind. A storm formed in the open ocean, far from the coast, will create winds that will begin to affect the surface of the water and therefore a swell will begin to appear. The wind, its direction, as well as speed, all this data can be seen on weather forecast maps. The wind begins to blow up the water, and “Small” (capillary) waves will begin to appear, initially they begin to move in the direction in which the wind is blowing.

The wind blows on a flat surface of water, the longer and stronger the wind begins to blow, the greater the impact on the surface of the water. Over time, the waves connect and the size of the wave begins to increase. The constant wind begins to form a large swell. The wind has a much greater impact on already created waves, although not large ones, much more than on the calm surface of the water.

The size of the waves directly depends on the speed of the blowing wind that forms them. Wind blowing at a constant speed can generate a wave of comparable size. And as soon as the wave acquires the size that the wind put into it, it becomes a fully formed wave that goes towards the shore.

Waves have different speeds and periods. Waves with a long period move quite quickly and cover greater distances than their counterparts with a lower speed. As they move away from the source of the wind, the waves combine to form a swell, which goes towards the coast. Waves that are no longer affected by the wind are called “Bottom waves.” These are the waves that all surfers hunt for.

What affects the size of a swell? There are three factors that influence the size of waves in the open ocean:
Wind speed – The higher the speed, the larger the resulting wave will be.
Duration of the wind - the longer the wind blows, similar to the previous factor - the wave will be larger.
Fetch (wind coverage area) – The larger the coverage area, the larger the wave produced.
When the wind stops influencing the waves, they begin to lose their energy. They will continue to move until they hit the protrusions of the bottom near some large oceanic island and the surfer will catch one of these waves in case of successful coincidences.

There are factors that influence the size of waves in a particular location. Among them:
The direction of the swell is what will allow the waves to come to the place we need.
Ocean floor - A swell moving from the open ocean encounters an underwater ridge of rocks, or a reef - forms large waves that can curl into a pipe. Or a shallow protrusion of the bottom will, on the contrary, slow down the waves and they will waste some of their energy.
Tidal cycle - many surf spots are directly affected by this phenomenon.