Rogue waves. Sea waves

Robber waves or wandering waves, monster waves are gigantic single waves 20-30 meters high, sometimes appearing larger in the ocean and exhibiting behavior uncharacteristic of sea waves.
Killer waves have a different origin from tsunamis and for a long time were considered fiction.

However, as part of the MaxWave project ("Maximum Wave"), which involved monitoring the surface of the world's oceans using the radar satellites ERS-1 and ERS-2 of the European Space Agency (ESA), recorded over three weeks throughout to the globe more than 10 single giant waves, the height of which exceeded 25 meters.

This forced the scientific community to reconsider their views, and despite the impossibility of mathematical modeling of the process of the occurrence of such waves, to recognize the fact of their existence.

1 Robber waves are waves whose height is more than twice the significant wave height.

Significant wave heights are calculated for a given period in a given region. To do this, a third of all recorded waves with the highest height are selected and their average height is found.

2 The first reliable instrumental evidence of the appearance of a rogue wave is considered to be instrument readings on the Dropner oil platform located in the North Sea.

On January 1, 1995, with a significant wave height of 12 meters (which is a lot, but quite common), a 26-meter wave suddenly appeared and hit the platform. The nature of the equipment damage corresponded to the specified wave height.

3 Robber waves can appear for no known reason in light winds and relatively small waves, reaching a height of 30 meters.

This is a mortal threat to even the most modern ships: the surface on which a giant wave crashes can experience pressure of up to 100 tons per square meter.

4 The most probable zones of wave formation in this case are called zones of sea currents, since in them the disturbances 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 significantly changing their structure. Similar packages have also been observed many times in practice. Characteristic Features Such groups of waves, confirming this theory, are that they move independently of other waves and have a small width (less than 1 km), and the heights drop off sharply at the edges.

5 In 1974, off the coast of South Africa, a rogue 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 unknown whether rogue waves were involved.

6 In 1980, the Russian tanker Taganrog Bay collided with a rogue wave". Description from the book by I. Lavrenov. " Mathematical modeling wind waves in a spatially inhomogeneous ocean”, op. based on the article by E. Pelinovsky and A. Slyunyaev. The sea state after 12 o'clock also decreased slightly and did not exceed 6 points. The ship's speed was slowed down to the very minimum, it obeyed the rudder and “played out” well on the wave. The tank and deck were not filled with water. Suddenly, at 13:01, the bow of the ship dropped slightly, and suddenly, at the very stem at an angle of 10-15 degrees to the ship's heading, the crest of a single wave was noticed, which rose 4-5 m above the forecastle (the bulwark of the forecastle was 11 m). The ridge instantly collapsed on the tank and covered the sailors working there (one of them died). The sailors said that the ship seemed to smoothly go down, sliding along the wave, and “buried” in the vertical section of its front part. No one felt the impact; the wave smoothly rolled over the tank of the ship, 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 Radar data analysis oil platform Goma in the North Sea showed, that over 12 years, 466 rogue waves were recorded in the available field of view.

While theoretical calculations showed that in this region the appearance of a rogue wave could occur approximately once every ten thousand years.

8 A rogue wave is usually described as a rapidly approaching wall of water of enormous height.

In front of it moves a depression several meters deep - a “hole in the sea.” Wave height is usually specified as the distance from the highest point of the crest to the lowest point of the trough. By appearance"Rogue 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, rogue waves are dangerous even for helicopters flying low over the sea: first of all, rescue ones.

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 death of rescue helicopters are similar to the result of a giant wave.

10 In the 2006 film Poseidon, the passenger liner Poseidon fell victim to a rogue wave., going to Atlantic Ocean on New Year's Eve.

The wave turned the ship upside down, and a few hours later it sank.

Based on materials:

Video on the topic “Killer Waves”:

With the help of this video lesson you can independently study the topic “Waves in the Ocean”. You will learn how waves are formed in the ocean and what they are like. What is the main reason for their occurrence? Why do some waves sometimes have whitecaps? What are the largest waves? After listening to the teacher's lecture, you will receive answers to these and other questions. interesting questions.

Topic: Hydrosphere

Lesson: Waves in the Ocean

The purpose of the lesson: to find out what waves there are and what are the reasons for their occurrence.

Ocean water is in constant movement. Main reason movement of water in the World Ocean - wind.

Light winds cause ripples in the water (see Figure 1). Ripples are small disturbances on the surface of a body of water.

Rice. 1. Ripples on the water ()

When the wind is strong, the waves become larger and stronger (see Fig. 2).

Rice. 2. Big waves ()

Rice. 3. Wave parts ()

When approaching a gently sloping shore, the lower part of the wave is slowed down by the ground, upper part waves move faster, as a result, a wave with splashes and foam breaks on the shore, this phenomenon is called surf(see Fig. 3, 4).

To protect berths, ports, marinas, and embankments from waves, breakwaters (breakwaters) are built that absorb wave energy (see Fig. 5).

Rice. 5. Breakwater

In addition to wind, the causes of wave formation can be human activity, movement earth's crust, collapses and landslides.

Tsunami - giant waves arising due to the collision of lithospheric plates (earthquakes) or volcanic eruptions.

Prices have enormous speed, height and strength. Approaching shallow water, the height of the tsunami increases to 30 meters! Tsunamis lead to destruction, loss of life, and flooding.

Tides- systematic fluctuations in sea level caused by the gravitational forces of the Moon and the Sun.

The Moon and Sun act like a magnet on water. The highest tides occur along the eastern coasts North America- Bay of Fundy.

Homework

Paragraph 26.

1. What reasons for the formation of waves do you know?

References

Main

1. Beginner course Geography: Textbook. for 6th grade. general education institutions / T.P. Gerasimova, N.P. Neklyukova. - 10th ed., stereotype. - M.: Bustard, 2010. - 176 p.

2. Geography. 6th grade: atlas. - 3rd ed., stereotype. - M.: Bustard; DIK, 2011. - 32 p.

3. Geography. 6th grade: atlas. - 4th ed., stereotype. - M.: Bustard, DIK, 2013. - 32 p.

4. Geography. 6th grade: cont. cards. - M.: DIK, Bustard, 2012. - 16 p.

Encyclopedias, dictionaries, reference books and statistical collections

1. Geography. Modern illustrated encyclopedia / A.P. Gorkin. - M.: Rosman-Press, 2006. - 624 p.

Literature for preparing for the State Exam and the Unified State Exam

1. Geography: Beginning course: Tests. Textbook manual for 6th grade students. - M.: Humanite. ed. VLADOS center, 2011. - 144 p.

2. Tests. Geography. 6-10 grades: Educational and methodological manual/ A.A. Letyagin. - M.: LLC "Agency "KRPA "Olympus": "Astrel", "AST", 2001. - 284 p.

Materials on the Internet

1. Federal Institute pedagogical measurements ().

2. Russian Geographical Society ().

Ocean waves are the forward movement of water in the ocean, associated with the vibration of water particles from frictional forces and wind resistance above the surface of the water.

• Ocean waves have crests (the peak of the wave) and troughs (the lowest point on the wave).
• The wavelength, or horizontal dimension of a wave, is determined by the horizontal distance between two crests or two troughs.
• The vertical size of a wave is determined by the vertical distance between them. Waves travel in groups called trains.

Waves vary in size and strength, depending on wind speed and friction on the surface of the water and external factors. Small waves created by the movement of a boat on the water are called wakes. Unlike strong winds and storms that can create large groups— wave trains of enormous energy.

In addition, underwater earthquakes and sudden movements on the seabed generate huge waves, called (incorrectly known as tidal waves) - can destroy entire coastlines.

Finally, a series of smooth rounded waves in open ocean, are called shafts. Waves are detected when wave energies leave the wave generation region. Swells can vary in size from small ripples to large flat crests.

Wave energy and motion

When studying waves, it is important to note the time when the wave appears - the water appears to be moving forward, but only Not large number the water is really moving. Instead, it is the energy of the wave that moves, since water is a flexible medium for transmitting energy, and therefore it appears to us that the water itself is moving.

In the open ocean, friction from moving waves generates energy in the water. This energy is transferred between water molecules in the ripple waves and is called a transition. When water molecules gain energy, they move forward a little and form a circular pattern.

As the water's energy moves towards the shore, the depth decreases and the diameter of the circular pattern also decreases. As the diameter decreases, the patterns become elliptical and the speed of the entire wave slows down.

The waves move in groups, they continue to arrive after the first wave and they are all forced to be closer friend to a friend as they slow down. They then grow in height and steepness. When the ocean waves become too high compared to the depth of the water, the stability of the wave is undermined and the entire wave capsizes onto the beach - a switch is formed. There are switches different types- all this is determined by the slope of the coast: a steep bank or coastline has a soft, gradual slope.

The exchange of energy between water molecules makes the ocean crisscrossed with waves traveling in all directions. Sometimes these waves meet and their interactions cause two types of interference.

• In the first case, the crests and troughs between two waves are consistent and combine. This causes a sharp increase in wave height.
• Waves also cancel each other out when crests meet or diverge.

Eventually, these waves do make it to the coast, and the varying sizes of moorings cause further disturbances in the ocean.

Waves of the ocean and coast

Ocean waves have a huge impact on shape coastline Earth. Their ability to erode rocks and add sediment to coastlines explains why they are an important component in the study of physical geography.

Ocean waves are one of the most powerful natural phenomena on Earth, they have a significant influence on the shape of the Earth's coastline. They can straighten the coastline. Sometimes, although headlands are composed of erosion-resistant rocks, the projection into the ocean causes waves to bend around them. The wave energy is distributed over several areas, and in different parts of the coast it turns out different quantity energy - the coast is shaped differently by waves.

One of the most famous examples ocean waves affecting coastlines, located in port or coastal currents. These ocean currents, created by waves, are refracted when they reach the shore. They form in the surf zone when the front of a wave is pushed into land and slows down. On the reverse wave, which is still in the deep waters and moves faster and flows parallel to the shore. How more water arrives, the more intensely a new portion of the current flow is pushed onto land, creating zigzags in the direction of the entry wave.

Longshore currents play an important role in the contours of coastlines because they exist in the surf zone and work with waves breaking on the shore. Thus, they receive a large amount of sand and other sediments and transport it to the shore, along the current. This material is called harbor drift and is essential to the development of many of the world's beaches.

The movement of sand, gravel and sediment with the drift of port waters is known as sedimentation. This is only one type of sediment affecting the coast, although it has its own characteristics, since it is formed exclusively through this process. Shoreline deposits are found in areas with soft topography.

Coastal landscapes resulting from deposition include barriers, spits, lagoons, and even beaches. A barrier, a spit, a relief - can partially block the mouth of the bay and cut off the bay from the ocean. Laguna - water body, which is cut off from the ocean by a barrier. The tombolo (sandy isthmus) is a landform that is created by sedimentation and connects the coast to the island. In addition to sedimentation, many coastal landforms create erosion. Some of them include rocks, platforms, sea ​​caves and arches.

Do you know? what's the most big wave, ever recorded by humans, was observed around Japanese island Ishigaki in 1971. The wave was 85 meters high

What causes the appearance of most waves in the oceans and seas, about the destructive energy of waves and about the most gigantic waves and the largest tsunamis that man has ever seen.

The highest wave

Most often, waves are generated by the wind: air moves the surface layers of the water column at a certain speed. Some waves can accelerate up to 95 km/h, and the wave can be up to 300 meters long; such waves travel huge distances across the ocean, but most often they kinetic energy extinguished, consumed even before they reach land. If the wind subsides, then the waves become smaller and smoother.

The formation of waves in the ocean follows certain patterns.

The height and length of the wave depend on the wind speed, the duration of its influence, and the area covered by the wind. There is a correspondence: the greatest height of a wave is one-seventh of its length. For example, a strong breeze generates waves up to 3 meters high, an extensive hurricane - on average up to 20 meters. And these are truly monstrous waves, with roaring foam caps and other special effects.

The highest normal wave of 34 meters was recorded in the Agulhas Current ( South Africa) in 1933 by sailors on board the American ship Ramapo. Waves of this height are called “rogue waves”: even a large ship can easily get lost in the gaps between them and die.

In theory, the height of normal waves can reach 60 meters, but such waves have not yet been recorded in practice.

In addition to the usual wind origin, there are other mechanisms of wave formation. The cause and epicenter of the birth of a wave can be an earthquake, a volcanic eruption, a sharp change in the coastline (landslides), human activity (for example, testing nuclear weapons) and even falling into the ocean of large celestial bodies- meteorites.

The biggest wave

This is a tsunami - a serial wave that is caused by some powerful impulse. The peculiarity of tsunami waves is that they are quite long; the distance between the crests can reach tens of kilometers. Therefore, in the open ocean, a tsunami does not pose a particular danger, since the height of the waves is on average no more than a few centimeters, in record cases - a meter and a half, but the speed of their propagation is simply unimaginable, up to 800 km / hour. From a ship on the open sea they are not noticeable at all. A tsunami acquires destructive power as it approaches the coast: reflection from the coast leads to a compression of the wavelength, but the energy does not disappear anywhere. Accordingly, its (wave) amplitude, that is, height, increases. It is easy to conclude that such waves can reach much higher heights than wind waves.

The worst tsunamis occur due to significant disturbances in the topography of the seabed, for example, tectonic faults or shifts, due to which billions of tons of water begin to abruptly move tens of thousands of kilometers at a speed jet plane. Disasters occur when this entire mass slows down on the shore, and its colossal energy first goes to increase in height, and ultimately collapses onto the land with all its power, a wall of water.

The most tsunami-hazardous places are bays with high banks. These are real tsunami traps. And the worst thing is that a tsunami almost always comes suddenly: in appearance, the situation at sea can be indistinguishable from low tide or high tide, an ordinary storm, people do not have time or do not even think about evacuating, and suddenly they are overtaken by a giant wave. Not many places have developed a warning system.

Territories with increased seismic activity– areas of special risk in our time. No wonder the name of this natural phenomenon is of Japanese origin.

The worst tsunami in Japan

The islands are regularly attacked by waves of different calibers, and among them there are truly gigantic ones that entail human casualties. Earthquake east coast the island of Honshu in 2011 caused a tsunami with a wave height of up to 40 meters. The earthquake is estimated to be the strongest in the recorded history of Japan. The waves struck along the entire coast, together with the earthquake they claimed the lives of more than 15 thousand people, many thousands were missing.

Another of the highest waves in Japanese history hit the western island of Hokkaido in 1741 as a result of a volcanic eruption; its height is approximately 90 meters.

The biggest tsunami in the world

In 2004, on the islands of Sumatra and Java, a tsunami caused strong earthquake V Indian Ocean, turned into a major disaster. According to various sources, from 200 to 300 thousand people died - a third of a million victims! To date, this particular tsunami is considered the most destructive in history.

And the record holder for wave height is named “Lituya”. This tsunami, which swept through Lituya Bay in Alaska at a speed of 160 km/h in 1958, was triggered by a giant landslide. The wave height was estimated at 524 meters.

Meanwhile, the sea is not always dangerous. There are “friendly” seas. For example, not a single river flows into the Red Sea, but it is the cleanest in the world. .
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Let's remember: Why are there waves at sea? What have you read about the action of waves on sea ​​shores?

Key words: sea ​​waves, tsunami.

1. Sea waves. The waters of the World Ocean are in continuous movement and mixing.

* The movement of the waters of the World Ocean can be oscillatory (waves) and translational (currents). Even a weak wind causes waves on the surface of the water. During oscillatory movements, water particles do not move horizontally. This is easy to see if you watch the float on the waves. The float only rises and falls, but does not move horizontally.

One of the main reasons for water movement is wind. As soon as the wind rises, even a weak one, waves begin to run across the sea. The wind picks up, and immediately white foamy scallops appear on the waves. They are called "lambs". This means that the waves are already more than 3 points. The waves are rolling and it seems that the sea water is moving towards the shore. No, the water doesn’t move, it’s just waves running along the surface of the sea. Water in waves rises and falls without mixing in the horizontal direction (Fig. 96).

Rice. 96. Waves and their elements.

* The wind acts on the surface of the water and disturbs its particles from a state of equilibrium. Waves are established when the wind speed is more than 1 m/s and covers only the upper layer of water.

Sea roughness is assessed on a 9-point scale. Points are determined by eye, based on the condition of the water surface. Excitement from 1 to 3 is weak, from 4 to 5 is moderate, from 6 to 7 is strong, from 8 to 9 is exceptional (see Table 3 in Appendix 1).

Waves actively destroy the coastal land, roll over and erase debris, and distribute it along the underwater slope. When approaching the shore, the speed of the lower part of the wave decreases, the height and steepness of the waves increase, and their crests overturn. Surf occurs near the shore and breakers appear on shallows, underwater and above-water rises (Fig. 97).

Rice. 97. Surf.

Waves can reach heights of up to 20 m or more. This is comparable to the height of a five-story building. They have enormous destructive force. There are fragments of rocks weighing up to 15 tons washed up on the shore. There are known cases of overturning stone blocks weighing 250 tons. To protect ships docked in seaports from the destructive force of waves, the ports are fenced with breakwaters made of especially strong reinforced concrete slabs.

* The waves reach their greatest heights in moderate latitudes, especially in the Southern Hemisphere, where the ocean occupies the largest space and the winds are strong and constant. Waves up to 20 - 30 m high are observed here. The average wave heights with moderate winds are 1 - 3, with significant winds - 6 - 10 m. The smallest waves are observed in equatorial latitudes, in the zone of calm and weak winds. In tropical latitudes, constant winds prevail, so the water surface is almost always in a turbulent state, but moderate waves prevail. In the seas, the waves are smaller than in the open ocean; their height is no more than 3 m.

2. Tsunami. In addition to wind, waves in the ocean are caused by movements of the earth's crust. Waves caused by strong underwater earthquakes, less commonly eruptions of underwater volcanoes, are called ts u n a m i(Fig. 98). They spread at high speed (400 - 800 km/h). This is the speed of a jet plane.

Tsunami is a Japanese word (“tsu” - bay, “nami” - wave). Therefore, a tsunami is a wave that floods a bay. These waves received this name because in the open ocean their height is insignificant (2 - 5 m), where they are little noticeable and not dangerous. Along the coast, the height of the waves increases greatly (up to 15 and even 40 m). Falling onto the shore, the waves destroy buildings, break ships, and, retreating, carry into the ocean everything they encounter on their way. Now in all dangerous areas there is a special service that quickly alerts the population of impending danger.

1. Under the influence of what forces do sea waves arise? 2. What causes a tsunami? 3. What effect do tsunamis have on the coast?