Ocean wave. World Ocean
Wave(Wave, surge, sea) - formed due to the adhesion of fluid and air particles; gliding over the smooth surface of the water, at first the air creates ripples, and only then, acts on its inclined surfaces, gradually developing 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 vertical movements occur, tending 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 - one! - 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.
The water element can be truly formidable! Just imagine what a person will feel when a wave is approaching, 30 meters high (about the size of a 9-story building). This unusual and rather rare natural phenomenon is called the “killer wave”. More recently, oceanologists attributed it to, but today scientists have irrefutable evidence of the existence of super-waves.
A killer wave, also called a rogue or white wave, appears as if from nowhere. It is absolutely impossible to predict the time and place of its formation. A huge mass of water, the size of which reaches 20..30 meters or more, poses a threat even to modern liners. A ship hit by a killer wave will sink much faster than the legendary Titanic. This will take no more than a few minutes.
Neptune's Terrible Revenge
The seafarers of the Middle Ages evoked awe and fear of the water element. There were numerous rituals designed to propitiate Neptune, the ruler of the seas and oceans. The Vikings carved drakkars from ash in the bow of their boats. The sea robbers believed that the noble tree had the ability to "reverse" storms and storms.
Of course, modern sailors no longer show honors to Neptune. But this does not mean that some natural phenomena cannot inspire superstitious horror even to an inveterate skeptic. People who were lucky enough to survive after meeting with a killer wave say that it “appeared as if from nowhere and disappeared to no one knows where.”
Does the killer wave generate infrasound?
Ancient sea legends tell about sirens - mythical mermaid women who lure sailors to the very bottom. According to beliefs, their voices are able to cloud the mind of a person and make him go to any madness, for example, throw himself overboard. Sometimes it even happened that the entire crew of the ship immediately turned out to be overboard. Subsequently, other navigators who encountered an empty ship could well have mistaken it for a legendary one.
You ask, what is the connection between the myth of the sirens and the huge killer wave? We will have to make a small digression and tell the reader about such an interesting natural phenomenon as infrasound. This term refers to a low-frequency sound that is not audible to the human ear, but meanwhile is able to influence the body. Some people begin to feel bad, others become confused.
At sea, infrasound can sometimes occur during a storm. Under the influence of a natural phenomenon, people begin to pursue hallucinations. For example, sailors may feel that the ship is on fire, which prompts them to throw themselves overboard. It is believed that it was infrasound that gave rise to legends about female sirens.
Now the most interesting thing is that some researchers suggest that the giant killer wave is also capable of generating infrasound. If this is true, then those who meet her at sea have little chance of survival.
Why do they appear?
One of the most popular hypotheses about the causes of the rogue wave is based on the superposition of waves of different lengths. In simple terms, several relatively small waves "merge" into one huge wave, which "lives" for some time, and then disappears. However, the calculations performed showed that the likelihood of this hypothesis is negligible.
Of interest is the fact that a killer wave can be not only a crest, but also a trough. However, the ship, faced with a natural trap, this will not be easier. Just imagine an unexpected fall into the abyss of the sea to the depth of a nine-story building!
Researchers of paranormal phenomena have also become interested in a phenomenon whose nature cannot be explained by scientists. According to one of the versions put forward, anomalous activity can become the cause of the appearance of superwaves. Some even suggest that the Atlantean race is still living at the bottom and is developing new technologies. Ufologists hypothesize that the appearance of killer waves is associated with UFO experiments.
Encounters with killer waves
The first documented case of a ship colliding with a killer wave occurred on February 7th, 1933. The victim of the raging elements was the ship "Ramapo", which belonged to the armed naval forces of the United States. An incredibly high shaft ambushed the ship in the waters of the Pacific Ocean. People who were lucky enough to survive recorded a wave of 34 meters moving at a speed of about 85 km / h.
In April 1966, the Michelangelo liner became another victim of the water element, which was hit by a wandering wave in the middle of the Atlantic. One of the sides and the bow of the ship was seriously damaged, 50 people were injured, and two passengers were washed out to sea.
The last time a sea "killer" was observed was in September 1995. This incident was recorded by the personnel of the Queen Elizabeth 2 liner. Brave sailors tried to "saddle" a huge shaft, 29 meters high. The place of collision with a natural phenomenon was the North Atlantic.
We invite you to watch the movie "Killer Wave" online. This short ten-minute video will surely arouse interest among fans of mysticism and marine themes.
Waves on the water are caused primarily by the wind. On a pond, mirror-smooth in calm weather, ripples appear in the wind, waves on the lake. There are places in the ocean where the height of wind waves reaches 30-40 m. This is due to the fact that in a shallow pond, a close bottom dampens water vibrations. And only in the open spaces of the ocean, the wind can seriously excite the surface of the water.
However, even huge waves are not always scary. After all, water in a wave does not run in the direction of the wind, but only moves up and down. More precisely, it moves in a small circle inside the wave. Only with a strong wind, the tops of the waves, picked up by the wind, outstrip the rest of the wave, causing collapses - then white lambs appear on the waves. 
It seems to us that a wave is running on the sea. In fact, the water inside the wave moves in a small circle. Near the shore, the lower part of the wave touches the bottom, and the neat circle collapses.
A wave can cause serious damage to a tall ship, especially a sailing ship, in which the height of the mast is much higher than the height of the sides. Such a ship is like a man being pushed under the knee. The raft is another matter. It protrudes quite a bit above the water, and tipping it over is like turning over a mattress lying on the floor.
When the sea wave approaches the shore, where the depth gradually decreases, its lower part slows down on the bottom. At the same time, the wave rises up, and collapses appear even on the most modest waves. Its upper part falls on the shore and immediately goes back along the bottom, continuing its circular motion. Therefore, it is so difficult to go ashore even with light waves. 
Waves near the shore can become destructive.
At steep rocky shores, the wave does not gradually slow down on the bottom, but immediately brings down all its power on the shore. Therefore, probably, the waves near the coast are called surf.
If the surface of the lake can be smooth, then the ocean is covered with waves almost constantly. The fact is that in the vast ocean there is always a place where wind waves form. And rarely will land be found that can stop these waves. The highest wind waves on the planet occur in the 40-50th latitudes of the Southern Hemisphere. Constant westerly winds blow there and there is almost no land that slows down the waves. 
Such a storm is caused by wind waves (a fragment of I.K. Aivazovsky's painting "Wave").
An earthquake or volcanic eruption shakes the sea surface not as often as the wind, but incomparably stronger. Sometimes this creates powerful waves that propagate at a speed of hundreds of meters per second. They can run around the Pacific Ocean, and sometimes the entire Earth around, before they begin to fade. They are called tsunamis. The height of a tsunami in the open ocean is only 1-2 m. But the wavelength (the distance between the crests) is large. Therefore, it turns out that each wave carries a huge mass of water moving at an enormous speed. When such a wave approaches the coast, it sometimes grows up to 50 m. There is little that can withstand a tsunami on the coast. Mankind has not yet come up with anything better than to evacuate the inhabitants of coastal areas deep into the mainland.
Killer waves or Wandering waves, monster waves are giant single waves 20-30 meters high, sometimes appearing more in the ocean and having behavior uncharacteristic of sea waves.
Killer waves have a different origin than tsunamis and have long been considered fiction.
However, within the framework of the MaxWave project (“Maximum wave”), which involved monitoring the surface of the world's oceans using the European Space Agency (ESA) radar satellites ERS-1 and ERS-2, more than 10 single giant waves were recorded around the globe in three weeks, whose height exceeded 25 meters.
This forced the scientific community to reconsider their views, and despite the impossibility of mathematical modeling of the process of occurrence of such waves, to recognize the fact of their existence.
1 Killer waves are waves whose height is more than twice the significant wave height.
Significant wave height is calculated for a given period in a given region. To do this, a third of all recorded waves with the highest height is selected, and their average height is found.
2 The first reliable instrumental evidence of the appearance of a killer wave is considered to be the readings of instruments on the oil platform "Dropner", located in the North Sea.
On January 1, 1995, with a significant wave height of 12 meters (which is quite a lot, but quite common), a 26-meter wave suddenly appeared and hit the platform. The nature of the damage to the equipment corresponded to the specified wave height.
3 Killer waves can appear for no known reason in light winds and relatively small waves, reaching a height of 30 meters.
This is a deadly threat even for the most modern ships: the surface on which a giant wave falls can experience pressure of up to 100 tons per square meter.
4 The most probable zones of wave formation in this case are the zones of sea currents, since in them the waves caused by the inhomogeneity of the current and the unevenness of the bottom are the most constant and intense. 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.
5 In 1974, off the coast of South Africa, a killer wave severely damaged the Norwegian tanker Wilstar..
Some scientists suggest that between 1968 and 1994, rogue waves destroyed 22 supertankers (and it is very difficult to destroy a supertanker). Experts, however, disagree on the causes of many shipwrecks: it is not known whether killer waves were involved in them.
6 In 1980, the Russian tanker Taganrog Bay collided with a killer wave.". Description from the book by I. Lavrenov. "Mathematical modeling of wind waves in a spatially inhomogeneous ocean", op. according to the article by E. Pelinovsky and A. Slyunyaev. The sea state after 12 o'clock also slightly decreased and did not exceed 6 points. The course of the ship was reduced to the smallest, it obeyed the helm and “played out” well on the wave. The tank and deck were not filled with water. Unexpectedly, at 13:01, the bow of the vessel sank somewhat, and suddenly, at the very stem at an angle of 10-15 degrees to the course of the vessel, a crest of a single wave was seen, which rose 4-5 m above the forecastle (the bulwark of the forecastle was 11 m). The crest instantly fell on the forecastle and covered the sailors working there (one of them died). The sailors said that the ship, as it were, went down smoothly, sliding along the wave, and “burrowed” into the vertical section of its frontal part. No one felt the impact, the wave smoothly rolled over the tank of the vessel, covering it with a layer of water more than 2 m thick. There was no continuation of the wave either to the right or to the left.
7 Analysis of radar data from the Goma oil platform in the North Sea showed, that in 12 years 466 killer waves were recorded in the accessible field of view.
While theoretical calculations showed that in this region the appearance of a killer wave could occur approximately once every ten thousand years.
8 Usually a killer wave is described as a rapidly approaching wall of water of great height..
A depression several meters deep moves in front of it - a “hole in the sea”. Wave height is usually specified precisely as the distance from the highest point of the crest to the lowest point of the trough. In appearance, "killer waves" are divided into three main types: "white wall", "three sisters" (a group of three waves), a single wave ("single tower").
9 According to some experts, killer waves are dangerous even for helicopters flying low over the sea: first of all, rescue.
Despite the seeming improbability of such an event, the authors of the hypothesis believe that it cannot be ruled out and that at least two cases of loss of rescue helicopters are similar to the result of a giant wave strike.
10 In the 2006 movie Poseidon, the Poseidon passenger liner fell victim to a killer wave. walking in the atlantic ocean on new year's eve.
The wave turned the ship upside down, and after a few hours it sank.
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