The surface of the seas and oceans is rarely calm: it is usually covered with waves, and the surf continuously beats on the shores.
An amazing sight: a massive cargo ship being played by giant storm waves in open ocean, seems no more than a nutshell. Disaster movies are replete with such pictures - 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 drops atmospheric pressure forms a complex chaotic wave field.
Running waves, boiling foam of the surf
Moving away from the cyclone that caused the storm, one can observe how the wave pattern is transformed, how the waves become more even and slender rows move one after another in one 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 their speed of propagation, are fairly constant. Two crests can be separated by a distance of up to 300 m, and such waves can reach a height of 25 m. Wave vibrations from such waves propagate to a depth of up to 150 m.
From the region of formation, swell waves propagate very far, even with complete calm. For example, cyclones passing off the coast of Newfoundland cause waves that reach the Bay of Biscay off the western coast of France in three days - almost 3000 km from the place of their formation.
When approaching the shore, as the depth decreases, these waves change their appearance. When wave oscillations reach the bottom, the movement of waves slows down, they begin to deform, which ends with the collapse of the ridges. Such waves are eagerly awaited by surfers. 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 with surfers all over the world.
Tides: global waves
Tides are a completely different phenomenon. 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 the tides is determined by the ratio of the periods daily rotation Earth around its axis and the rotation of the Moon around the Earth. The sun is also involved 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 value of the tides depends, therefore, on relative position Earth, Moon and Sun, which changes during the month. When they are on the same line (which happens on 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 positions of the sea level here is about 19.6 m.
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Man perceives many natural phenomena as self-evident. We are accustomed to summer, autumn, winter, rain, snow, waves and do not think about the reasons. And yet, why do waves form in the sea? Why do ripples appear on the surface of the water even in complete calm?
Origin
There are several theories explaining the origin of sea and ocean waves. They are formed due to:
- changes in atmospheric pressure;
- ebbs and flows;
- underwater earthquakes and volcanic eruptions;
- ship movements;
- strong wind.
To understand the mechanism of formation, one must remember that water is agitated and oscillates involuntarily - as a result of physical impact. A pebble, a boat, a hand touching it set the liquid mass in motion, creating vibrations different strength.
Characteristics
Waves are also the movement of water on the surface of a reservoir. They are the result of the adhesion of air particles and liquid. At first, water-air symbiosis causes ripples on the surface of the water, and then causes the water column to move.
Size, length and strength vary, depending on the strength of the wind. During a storm, powerful pillars rise to 8 meters and stretch in length for almost a quarter of a kilometer.
Sometimes the force is so destructive that it falls on the coastal strip, uproots umbrellas, showers and other beach buildings, demolishes everything in its path. And this despite the fact that fluctuations are formed several thousand kilometers from the coast.
All waves can be divided into 2 categories:
- wind;
- standing.
wind
Windmills, as the name implies, are formed under the influence of wind. Its gusts rush at a tangent, forcing the water and forcing it to move. The wind pushes the liquid mass forward in front of it, but gravity slows down the process, pushing it back. Movements on the surface, resulting from the influence of two forces, resemble ups and downs. Their peaks are called crests, and their bases are called soles.
Having found out why waves form on the sea, the question remains open as to why they make oscillatory movements up and down? The explanation is simple - the inconstancy of the wind. He then quickly and impetuously swoops, then subsides. The height of the crest, the frequency of oscillations directly depend on its strength and power. If the speed of movement and the strength of the air currents exceed the norm, a storm rises. Another reason is renewable energy.
Renewable energy
Sometimes the sea is completely calm, and the waves are formed. Why? Oceanographers and geographers attribute this phenomenon to renewable energy. Water fluctuations are its source and ways to keep the potential for a long time.
In real life, it looks like this. The wind creates a certain amount of vibration in the pond. The energy of these oscillations will last for several hours. During this time, liquid formations cover a distance of tens of kilometers and "moor" in areas where it is sunny, there is no wind, and the reservoir is calm.
standing
Standing or solitary waves arise due to shocks on the ocean floor, characteristic of earthquakes, volcanic eruptions, and also due to a sharp change in atmospheric pressure.
This phenomenon is called seiches, which translates from French how to "swing". Seiches are typical for bays, gulfs and some seas; they pose a danger to beaches, structures in the coastal strip, ships moored at the pier and people on board.
constructive and destructive
Formations that overcome long distances and do not change shape and do not lose energy, hit the coast and break. At the same time, each run-up has a different effect on the coastal strip. If it washes the shore, it is classified as constructive.
The destructive surge of water falls with its power on the coast, destroying it, gradually washing away sand and pebbles from the beach strip. In this case a natural phenomenon classified as destructive.
Destruction is of different destructive power. Sometimes it is so powerful that it brings down slopes, splits cliffs, separates rocks. Over time, even the hardest rocks are destroyed. America's largest lighthouse was built at Cape Hatteras in 1870. Since then, the sea has moved almost 430 meters inland, washing away the coastline and beaches. This is just one of dozens of facts.
Tsunamis are a type of destructive water formations characterized by great destructive power. The speed of their movement reaches 1000 km / h. This is higher than that of a jet aircraft. At depth, the height of the tsunami crest is small, but near the coast they slow down, but increase the height to 20 meters.
In 80% of cases, tsunamis are the result of underwater earthquakes, in the remaining 20% - volcanic eruptions and landslides. As a result of earthquakes, the bottom shifts vertically: one part of it sinks, and the other part rises in parallel. Fluctuations of different strength are formed on the surface of the reservoir.
Anomalous Assassins
They are also known as wanderers, monsters, anomalous, and more characteristic of the oceans.
Even 30-40 years ago, sailors' stories about anomalous water fluctuations were considered fiction, because in the existing scientific theories and eyewitness accounts did not fit. A height of 21 meters was considered the limit for oceanic and sea vibrations.
We have long been accustomed to many phenomena occurring on our planet, without thinking at all about the nature of their occurrence and the mechanics of their action. This is climate change, and the change of seasons, and the change of time of day, and the formation of waves on the sea and in the oceans.
And today we just want to pay attention to the last question, the question of why waves form on the sea.
Why do waves form in the sea
There are theories that waves in the seas and oceans arise due to pressure drops. However, these are often just the assumptions of people who quickly try to find an explanation for such a natural phenomenon. In reality, things are somewhat different.
Remember what makes the water "worry". This is a physical effect. Throwing something into the water, running a hand over it, hitting the water sharply, vibrations of different sizes and frequencies will certainly begin to go through it. Based on this, it can be understood that waves are the result of a physical impact on the surface of the water.
However, why do large waves appear on the sea, coming to the shore from afar? Another natural phenomenon is to blame - the wind.
The fact is that gusts of wind pass over the water along a tangent line, exerting a physical effect on the sea surface. It is this action that pumps water and makes it move in waves.
Someone, of course, will ask another question about why the waves on the sea and in the ocean move with oscillatory movements. However, the answer to this question is even simpler than the very nature of waves. The fact is that the wind has a non-permanent physical effect on the surface of the water, because it is directed towards it by gusts of different strength and power. This affects the fact that the waves have a different size and frequency of oscillation. Of course, strong waves, a real storm, occur when the wind exceeds the norm.
Why are there waves on the sea without wind
A very reasonable nuance is the question of why there are waves on the sea even if there is absolute calm, if the wind is completely absent.
And here the answer to the question will be the fact that water waves are an ideal source of renewable energy. The fact is that waves are able to store their potential for a very long time. That is, the wind that brought the water into action, creating a certain number of oscillations (waves), can be enough for the wave to continue its oscillation for a very long time, and the wave potential itself has not exhausted itself even after tens of kilometers from the point of origin of the wave.
That's all the answers to questions about why there are waves on the sea.
Where do giant waves come from?
What causes the appearance of most waves in the oceans and seas, about the energy of the waves and about the most gigantic waves.
The main reason for the appearance of ocean waves is the influence of winds on the water surface. The speed of some waves can develop and even exceed 95 km per hour. Ridge from ridge can be separated by 300 meters. They travel great distances across the surface of the ocean. Most of their energy is used up before they reach land, perhaps bypassing the deepest place in the world – Mariana Trench. And yes, they are getting smaller. And if the wind calms down, then the waves become calmer and smoother.
If there is a strong breeze in the ocean, then the height of the waves usually reaches 3 meters. If the wind starts to become stormy, then they can become 6 m. In a strong gale, their height can already be more than 9 m and they become steep, with abundant spray.
During a storm, when visibility is difficult in the ocean, the height of the waves exceeds 12 meters. But during a severe storm, when the sea is completely covered with foam and even small ships, yachts or ships (and not just fish, even the biggest fish) can simply get lost between 14 waves.
The beat of the waves
Large waves gradually wash away the shores. Small waves can slowly level the beach with sediment. Waves hit the shores at a certain angle, therefore, sediment washed away in one place will be carried out and deposited in another.
During the strongest hurricanes or storms, such changes can occur that huge stretches of the coast can suddenly transform significantly.
And not only the coast. Once upon a time, in 1755, very far from us, waves of 30 meters high blew Lisbon off the face of the earth, submerging the city's buildings under tons of water, turning them into ruins and killing more than half a million people. And it happened on a big Catholic holiday - All Saints' Day.
killer waves
The largest waves are usually observed along the Needle Current (or Agulhas Current), which is off the coast South Africa. Here it was also noted highest wave in the ocean. Its height was 34 m. In general, the largest wave ever seen was recorded by Lieutenant Frederick Margo on a ship on its way from Manila to San Diego. It was February 7, 1933. The height of that wave was also about 34 meters. Sailors gave the nickname "killer waves" to such waves. As a rule, an unusually high wave is always preceded by the same deep depression (or dip). It is known that in such depressions-failures disappeared a large number of ships. By the way, the waves that form during the tides are not connected with the tides. They are caused by an underwater earthquake or volcanic eruption on the sea or ocean floor, which creates the movement of huge masses of water and, as a result, large waves.
