Let's talk about the Black Sea waves. The frequent recurrence of strong winds, the significant size of the sea, great depths, and the weak indentation of the coastline contribute to the development of waves. The highest wave heights in the Black Sea are 14 meters. The length of such waves is 200 meters. On the approaches to Sochi, the maximum wave height is 6 meters, the length is 120 meters.
It is possible to evaluate the excitement not only by the elements of the waves (height, length, period), but also by the degree.

Evaluation of the degree of excitement is made on a special scale. So, for example, on this scale, 1 point - the height of the waves does not exceed 25 centimeters, 2 points - the height of the waves 25-75 centimeters, 3 points - 0.75-1.25 meters, 4 points - 1.25-2 meters. In total, the scale has 9 points. It is possible to describe the state of the sea surface during wind waves: 1 point - the appearance of ripples during gusts of wind, 2 points - transparent vitreous foam appears on the crests of the waves, 3 points - separate white "lambs" appear on the crests of the waves, 4 points - the whole sea is covered with "lambs " etc.

The scale of wind strength (where the correspondence of points and meters per second is given) has 12 points. The strength of the storm is determined by the strength of the wind. Therefore, the expression "storm 10 points" will be correct, but the expression "10 points excitement" is incorrect. In the Black Sea, the frequency of strong waves is low. During the most "stormy" year, a wave of 6-9 points is not observed for more than 17 days.

A distinctive feature of the Black Sea waves is their "stability". This is the so-called swell, which has a longer period of oscillation than the wind wave. A swell is a wave observed with little or no wind ("dead swell"). However, the origin of these waves is associated with the activity of the wind. Waves formed in the storm zone, which is located at this time in the western part of the Black Sea, may come to the Caucasian coast of the sea. Near the Caucasian shores, the winds can be weak, and the wave can be large. This will be the swell. The existence of a swell is associated with the concept of the “ninth wave”, which has long been common among our sailors, known to many from the painting by Aivazovsky. It cannot be said that the idea of ​​the ninth wave was completely without any foundation. The fact is that swell waves, as a rule, go in groups, and in the center of the group there are the largest waves, and at the edges of the wave of a smaller height. Some wave of this group may indeed be much larger than the others, but it is not known which wave it will be in a row - the third, fifth or ninth, and with which wave to start the count. Thus, one should not think at all that it is the ninth wave that is the most terrible. By the way, among the ancient Greeks, every third shaft was considered the most dangerous, and among the Romans - the tenth.

Sailors endure swell more easily than the Azov or Caspian wind wave - "bumpy" with a period of 3-5 seconds. However, the swell has the unpleasant feature that it gives a strong surf near the shore. The wave, almost imperceptible in the sea due to its small steepness, falls on the shore with tremendous force.

Stormy sea video on the Black Sea (Anapa)

Swimming in the sea during a storm is very dangerous. It is usually quite difficult to overcome the zone of breakers and get into the open sea, where you can float relatively calmly, rising and falling with each wave. It is much more difficult for a tired person to get ashore again through a barrier of crumbling and foaming waves. Every now and then he is carried back to the sea. There were cases when even people who knew how to swim well drowned here. That is why on city and sanatorium beaches they hang out signs with warning inscriptions during a storm. It is appropriate to recall here that all animals, jellyfish, sea fleas and other organisms leave the dangerous surf zone before the storm, seagulls fly ashore, however, you can see how some people choose the time of the storm in order to demonstrate their “bravery” by swinging on waves.

The force of the waves hitting the shores and structures is enormous. Near Sochi, it exceeds 100 tons per square meter. During such impacts, bursts with a height of several tens of meters occur. The colossal energy of breaking waves is spent on crushing rocks and moving sediments. Without the influence of waves, the rivers would gradually roll down to the depth, while the waves return them to the coast and force them to move along it. For example, along the Caucasian coast of the Black Sea there is a constant flow of sediment. From Tuapse to Pitsunda, waves move 30-35 thousand cubic meters of sediment per year.

Where there is a beach, the waves lose most of their energy. Where there is none, they destroy the bedrock. During the Great Patriotic War, the erosion of the coast south of the port of Sochi reached 4 meters per year. Immediately after the end of the war, bank protection works were started in this area, and the erosion of the coast stopped.

A railway runs along the Caucasian coast of the sea. Sanatoriums, theaters, maritime stations and residential buildings were built in the coastal zone. Therefore, the sea coast must be protected from erosion. The best protection in this regard is the beach, where the waves break before reaching the shore. To fix the beaches, groins and underwater breakwaters are being built. These structures prevent the movement of pebbles along the coast to other areas and its withdrawal into the depths of the sea. This is how the beach grows.

Are there tsunami waves in the Black Sea caused by earthquakes, as we have in the Far East? There are tsunamis, but they are very weak. They are recorded only by devices and are not even felt by a person.

To what depth do ordinary waves propagate? Already at a depth of 10 meters they are smaller than on the surface, and at a depth of 50 meters they are completely invisible. Maybe in the depths reigns peace, which nothing disturbs? No, it's not. There are their own, so-called internal waves. They differ from surface ones in their size (tens of meters in height and kilometers in length), and the reasons for their origin are different. They arise, as a rule, at the interface between two layers with different densities. Although they are not visible on the surface, submarines face great difficulties during such an “underwater storm”.

Initially, the 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, in connection with this, a swell begins to occur. Wind, its direction, as well as speed, all these data can be seen on weather forecast maps. The wind begins to inflate the water, and "Small" (capillary) waves will begin to appear, initially they begin to move in the direction in which the wind blows.

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

The size of the waves directly depends on the speed of the blowing wind that forms them. A 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 coast.

Waves have different speeds and periods. Waves with a long period move fast enough and cover greater distances than their counterparts with a lower speed. As you move away from the source of the wind, the waves combine to form a swell that 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 affect the size of waves in the open ocean:
Wind speed - The higher the speed, the larger the wave will eventually be.
Wind duration - the longer the wind blows, similarly to the previous factor, the wave will be larger.
Fetch (wind coverage area) - The larger the coverage area, the larger the wave.
When the effect of the wind on the waves stops, they begin to lose their energy. They will continue to move until such time as they hit the ledges of the bottom of some large oceanic island and the surfer catches one of these waves in case of good luck.

There are factors that affect the size of the 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 bumps into an underwater ridge of rocks, or a reef - forms large waves with which they can twist into a pipe. Or a shallow ledge of the bottom - on the contrary, it will slow down the waves and they will spend part of their energy.
The tidal cycle - many surf spots are directly dependent on this phenomenon.

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 the wind is blowing.

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

The wind has a greater effect on small waves than on a calm surface of the water.

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

The generated waves have different wave speeds and periods. (More details in the article) Waves with a long period move faster and cover greater distances than their slower counterparts. As they move away from the wind source (propagation), the waves form lines of swells, which inevitably roll onto the shore. Most likely, you are familiar with the concept of a set of waves!

Waves that are no longer affected by the wind are called ground waves (ground swell)? This is exactly what surfers are looking for!

What affects the size of a swell?

There are three main factors that affect the size of waves on the high seas.
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 influence of the wind on them stops, the waves begin to lose their energy. They will move until the moment when 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 affect 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- Swell, moving from the depths of the ocean to the 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 are completely dependent on it.

Find out how the best waves come about.

Wave(Wave, surge, sea) - formed due to the adhesion of fluid and air particles; sliding on the smooth surface of the water, at first the air creates ripples, and only then, acts on its inclined surfaces, gradually develops the excitement of the water mass. Experience has shown that water particles do not have translational motion; moves only vertically. Sea waves are the movement of water on the sea surface, which occurs at regular intervals.

The highest point of the wave is called crest or the top of the wave, and the lowest point - sole. Height wave is the distance from the crest to its sole, and length is the distance between two ridges or soles. The time between two ridges or soles is called period waves.

The main causes of occurrence

On average, the height of a wave during a storm in the ocean reaches 7-8 meters, usually it can stretch in length - up to 150 meters and up to 250 meters during a storm.

In most cases, sea waves are formed by the wind. The strength and size of such waves depend on the strength of the wind, as well as its duration and "acceleration" - the length of the path on which the wind acts on the water surface. Sometimes waves that break on the coast can originate thousands of kilometers from the coast. But there are many other factors in the occurrence of sea waves: these are the tide-forming forces of the Moon, the Sun, fluctuations in atmospheric pressure, eruptions of underwater volcanoes, underwater earthquakes, and the movement of ships.

Waves observed in other water spaces can be of two kinds:

1) wind, created by the wind, taking on the cessation of the action of the wind, a steady character and called steady waves, or swell; Wind waves are created due to the effect of wind (movement of air masses) on the surface of the water, that is, injection. The reason for the oscillatory movements of the waves becomes easily understood if one notices the effect of the same wind on the surface of a wheat field. The inconsistency of wind flows, which create waves, is clearly visible.

2) Waves of displacement, or standing waves, are formed as a result of strong shocks at the bottom during earthquakes or excited, for example, by a sharp change in atmospheric pressure. These waves are also called solitary waves.

Unlike tides, tides and currents, waves do not move masses of water. The waves are coming, but the water stays where it is. A boat that rocks on the waves does not float with the wave. It will be able to move a little on an inclined, only thanks to the force of the earth's gravity. The water particles in the wave move along the rings. The farther these rings are from the surface, the smaller they become and, finally, disappear altogether. Being in a submarine at a depth of 70-80 meters, you will not feel the effect of sea waves even during the strongest storm on the surface.

Types of sea waves

Waves can travel vast distances without changing shape and losing little or no energy, long after the wind that caused them has died down. Breaking on the shore, sea waves release huge energy accumulated during the journey. The force of continuously breaking waves changes the shape of the shore in different ways. Overflowing and rolling waves wash the shore and therefore are called constructive. Waves crashing on the coast gradually destroy it and wash away the beaches that protect it. Therefore they are called destructive.

Low, wide, rounded waves away from the shore are called swell. Waves make water particles describe circles, rings. The size of the rings decreases with depth. As the wave approaches the sloping shore, the water particles in it describe more and more flattened ovals. Approaching the shore, the sea waves can no longer close their ovals, and the wave breaks. In shallow water, water particles can no longer close their ovals, and the wave breaks. Capes are formed from harder rock and are destroyed more slowly than neighboring sections of the coast. Steep, high sea waves undermine the rocky cliffs at the base, forming niches. Cliffs sometimes collapse. The terrace smoothed by the waves is all that remains of the rocks destroyed by the sea. Sometimes water rises along vertical cracks in the rock to the top and breaks out to the surface, forming a funnel. The destructive force of the waves expands the cracks in the rock, forming caves. When the waves undermine the rock from two sides until they join in a gap, arches form. When the top of the arch falls into the sea, stone pillars remain. Their bases are undermined, and the pillars collapse, forming boulders. The pebbles and sand on the beach are the result of erosion.

Destructive waves gradually wash away the coast and carry away sand and pebbles from sea beaches. Bringing down the entire weight of their water and washed-away material on the slopes and cliffs, the waves destroy their surface. They force water and air into every crack, every crevice, often with the energy of an explosion, gradually parting and weakening the rocks. Breakaway rock fragments are used for further destruction. Even the hardest rocks are gradually destroyed, and the land on the coast is changed by the action of the waves. Waves can destroy the seashore with amazing speed. In Lincolnshire, England, erosion (destruction) is advancing at a rate of 2 m per year. Since 1870, when the largest lighthouse in the United States was built at Cape Hatteras, the sea has washed away the beaches 426 m inland.

Tsunami

Tsunami These are waves of enormous destructive power. They are caused by underwater earthquakes or volcanic eruptions and can cross oceans faster than a jet plane: 1000 km/h. In deep waters, they can be less than one meter, but as they approach the shore, they slow down their run and grow up to 30-50 meters before collapsing, flooding the shore and sweeping away everything in their path. 90% of all recorded tsunamis occur in the Pacific Ocean.

The most common reasons.

About 80% of tsunami generations are underwater earthquakes. During an earthquake under water, a mutual displacement of the bottom occurs along the vertical: part of the bottom falls, and part rises. On the surface of the water, oscillatory movements occur along the vertical, trying to return to the initial level - the mean sea level - and generates a series of waves. Not every underwater earthquake is accompanied by a tsunami. Tsunamigenic (that is, generating a tsunami wave) is usually an earthquake with a shallow source. The problem of recognizing the tsunamigenicity of an earthquake has not yet been solved, and warning services are guided by the magnitude of the earthquake. The strongest tsunamis are generated in subduction zones. Also, it is necessary that the underwater push entered into resonance with wave oscillations.

Landslides. Tsunamis of this type occur more frequently than was estimated in the 20th century (about 7% of all tsunamis). Often an earthquake causes a landslide and it also generates a wave. On July 9, 1958, as a result of an earthquake in Alaska, a landslide occurred in Lituya Bay. A mass of ice and terrestrial rocks collapsed from a height of 1100 m. A wave formed, reaching a height of more than 524 m on the opposite shore of the bay. Such cases are quite rare and are not considered as a standard. But much more often underwater landslides occur in river deltas, which are no less dangerous. An earthquake can cause a landslide and, for example, in Indonesia, where shelf sedimentation is very large, landslide tsunamis are especially dangerous, as they occur regularly, causing local waves over 20 meters high.

Volcanic eruptions account for approximately 5% of all tsunami events. Large underwater eruptions have the same effect as earthquakes. In strong volcanic explosions, not only are the waves from the explosion, but water also fills the cavities from the erupted material or even the caldera, resulting in a long wave. A classic example is the tsunami that formed after the Krakatoa eruption in 1883. Huge tsunamis from the Krakatau volcano were observed in harbors around the world and destroyed a total of more than 5,000 ships, killing about 36,000 people.

Signs of a tsunami.

• sudden fast withdrawal of water from the shore for a considerable distance and drying of the bottom. The further the sea recedes, the higher the tsunami waves can be. People who are on the shore and do not know about danger, may stay out of curiosity or to collect fish and shells. In this case, it is necessary to leave the coast as soon as possible and move away from it to the maximum distance - this rule should be followed, for example, while in Japan, on the Indian Ocean coast of Indonesia, Kamchatka. In the case of a teletsunami, the wave usually approaches without the water receding.
• Earthquake. The epicenter of an earthquake is usually in the ocean. On the coast, the earthquake is usually much weaker, and often there is none at all. In tsunami-prone regions, there is a rule that if an earthquake is felt, it is better to move further from the coast and at the same time climb a hill, thus preparing in advance for the arrival of a wave.
• unusual drift ice and other floating objects, the formation of cracks in the fast ice.
• Huge reverses at the edges of immovable ice and reefs, the formation of crowds, currents.

killer waves

killer waves(Wandering waves, monster waves, freak wave - an anomalous wave) - giant waves that arise in the ocean, more than 30 meters high, have behavior unusual for sea waves.

Even some 10-15 years ago, scientists considered the stories of sailors about gigantic killer waves that appear out of nowhere and sink ships, just maritime folklore. Long time wandering waves were considered fiction, since they did not fit into any of the mathematical models that existed at that time for calculating the occurrence and their behavior, because waves over 21 meters high in the oceans of planet Earth cannot exist.

One of the first descriptions of a monster wave dates back to 1826. Its height was more than 25 meters and it was noticed in the Atlantic Ocean near the Bay of Biscay. Nobody believed this message. And in 1840, the navigator Dumont d'Urville ventured to appear at a meeting of the French Geographical Society and declare that he had seen a 35-meter wave with his own eyes. Those present laughed at him. But stories about huge ghost waves that appeared suddenly in the middle of the ocean, even with a small storm, and their steepness resembled sheer walls of water, it became more and more.

Historical evidence of "killer waves"

So, in 1933, the USS Ramapo was caught in a storm in the Pacific Ocean. For seven days the ship was thrown over the waves. And on the morning of February 7, a shaft of incredible height suddenly crept up from behind. At first, the ship was thrown into a deep abyss, and then lifted almost vertically onto a mountain of foaming water. The crew, who were lucky enough to survive, recorded a wave height of 34 meters. She moved at a speed of 23 m / s, or 85 km / h. So far, this is considered the highest rogue wave ever measured.

During the Second World War, in 1942, the Queen Mary liner carried 16,000 American troops from New York to Great Britain (by the way, a record for the number of people transported on one ship). Suddenly there was a 28-meter wave. "The upper deck was at its usual height, and suddenly - once! - she abruptly went down," recalled Dr. Norval Carter, who was on board the ill-fated ship. The ship banked at an angle of 53 degrees - if the angle had been at least three degrees more, death would have been inevitable. The story of "Queen Mary" formed the basis of the Hollywood film "Poseidon".

However, on January 1, 1995, a wave 25.6 meters high, called the Dropner wave, was first recorded on the Dropner oil platform in the North Sea off the coast of Norway. The "Maximum Wave" project made it possible to take a fresh look at the causes of the death of dry cargo ships that carried containers and other important cargo. Further research recorded more than 10 single giant waves around the globe in three weeks, the height of which exceeded 20 meters. The new project was called Wave Atlas (Atlas of waves), which provides for the compilation of a worldwide map of observed monster waves and its subsequent processing and addition.

Causes

There are several hypotheses about the causes of extreme waves. Many of them lack common sense. The simplest explanations are based on the analysis of a simple superposition of waves of different lengths. Estimates, however, show that the probability of extreme waves in such a scheme turns out to be too small. Another noteworthy hypothesis suggests the possibility of wave energy focusing in some structures of surface currents. These structures, however, are too specific for the mechanism of energy focusing to explain the systematic occurrence of extreme waves. The most reliable explanation for the occurrence of extreme waves should be based on the internal mechanisms of nonlinear surface waves without involving external factors.

Interestingly, such waves can be both crests and troughs, which is confirmed by eyewitnesses. Further research involves the effects of nonlinearity in wind waves, which can lead to the formation of small groups of waves (packets) or individual waves (solitons) that can travel long distances without significant changes in their structure. Similar packages have also been repeatedly observed in practice. The characteristic features of such groups of waves, confirming this theory, is that they move independently of other waves and have a small width (less than 1 km), with heights dropping sharply at the edges.

However, it has not yet been possible to fully elucidate the nature of anomalous waves.

How are waves formed? Surf reports and wave forecasts are based on scientific research and weather modeling. In order to know what waves will form in the near future, it is important to understand how they are formed.

The main reason for the formation of waves is the wind. The waves best suited for surfing are formed as a result of the interaction of winds over the surface of the ocean, away from the shore. Wind action is the first stage of wave formation.

Winds blowing in a given area from the shore can also cause waves, but they can also lead to a deterioration in the quality of breaking waves.

It has been established that winds blowing from the sea usually lead to the formation of unstable and uneven waves, since they affect the direction of the wave. The winds blowing off the coast serve in a sense as a sort of balancing force. The wave travels many kilometers from the depths of the ocean to the shore, and the wind from the land has a “braking” effect on the face of the wave, allowing it not to break for longer.

Low pressure areas = good waves for surfing

Theoretically, areas of low pressure contribute to the formation of good, powerful waves. In the depths of such areas, the wind speed is higher, and gusts of wind form more waves. The friction created by these winds helps to form powerful waves that travel thousands of kilometers until they hit the final obstacles, that is, the coastal areas where people live.

If the winds generated in areas of low pressure continue to blow on the surface of the ocean for a long time, then the waves become more intense, as energy accumulates in all the waves that are formed. In addition, if winds from low pressure areas affect a very large area of ​​the ocean, then all the resulting waves concentrate even more energy and power in themselves, which leads to the formation of even larger waves.

From waves in the ocean to waves for surfing: the seabed and other obstacles

We have already analyzed how waves are formed in the sea and the waves generated by it, but after the “birth”, such waves still have to travel a huge distance to the coast. Waves originating in the ocean have a long way to go before they reach land.

During their journey, before the surfers get on them, these waves will have to overcome other obstacles. The height of the emerging wave does not match the height of the waves on which the surfers ride.

Moving through the ocean, the waves are exposed to the roughness of the seabed. When giant moving masses of water overcome elevations on the sea floor, the total amount of energy concentrated in the waves changes.

For example, continental shelves at a distance from the coast resist moving waves due to the force of friction, and by the time the waves reach coastal waters, where the depth is shallow, they already lose their energy, strength and power.

When waves move through deep waters without encountering obstacles in their path, they tend to hit the coastline with great force. The depths of the ocean floor and their changes over time are studied as part of bathymetric studies.

Using the depth map, it is easy to find the deepest and shallowest areas of the oceans of our planet. The study of the topography of the seabed is of great importance in preventing the wrecks of ships and cruise liners.

In addition, by studying the structure of the bottom, you can get valuable information for predicting surf at a particular surf spot. When the waves reach shallow water, their speed usually decreases. Despite this, the wavelength shortens and the crest increases, resulting in an increase in wave height.

Sandbanks and wave crest increase

Sandbanks, for example, always change the nature of beach breaks. That is why the quality of the waves changes over time for better or worse. The sandy undulations on the ocean floor allow for the formation of well-defined, concentrated wave crests from which surfers can begin their slide.

When a wave hits a new sandbank, a wave usually forms a new crest, since such an obstacle causes the crest to rise, that is, the formation of a wave suitable for surfing. Other obstacles to waves include groins, sunken ships, or simply natural or artificial reefs.

Waves are generated by the wind and, as they move, are affected by the topography of the seabed, precipitation, tides, rip currents along the coasts, local winds and uneven bottoms. All these weather and geological factors contribute to the formation of waves suitable for surfing, kitesurfing, windsurfing and boogie surfing.

Wave Forecasting: Theoretical Foundations

• Waves with a long period tend to be larger and more powerful.
• Waves with a short period tend to be smaller and weaker.
• The period of a wave is the time between the formation of two distinct crests.
• The frequency of waves is the number of waves passing through a certain point in a certain time.
• Big waves move fast.
• Small waves move slowly.
• In areas of low pressure, intense waves form.
• The areas of low pressure are characterized by rainy weather and cloudiness.
• High pressure areas are characterized by warm weather and clear skies.
• Larger waves form in deep coastal areas.
• Tsunamis are not suitable for surfing.