Why do waves form in the sea? How do waves appear? How waves are made in 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- The 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), off the coast of 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 a large number of ships disappeared in such hollows-failures. 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.
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 of different strengths.
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 is translated from French as "to sway." 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, the natural phenomenon is 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 eyewitness accounts did not fit into the existing scientific theories and calculations. A height of 21 meters was considered the limit for oceanic and sea vibrations.
The main reason for the formation of waves is the wind blowing over the water. Therefore, the magnitude of the wave depends on the strength and time of its impact. Due to the wind, water particles rise up, sometimes breaking away from the surface, but after some time, under the influence of natural gravity, they inevitably fall down. From afar, it may seem that the wave is moving forward, but in fact, if this wave, of course, is not a tsunami, (tsunamis have a different nature of occurrence), it only descends and rises. So, for example, a sea bird that has landed on the surface of a rough sea will sway on the waves, but will not budge.
Only near the shore, where it is no longer deep, the water moves forward, rolling onto the shore. By the way, according to the scallop of spray from detached drops forming a crest on a wave, experienced sailors determine the degree of sea disturbance, if the crest and foam on it have just begun to form, then the sea is 3 points.
What kind of sea wave is called a coast.
Waves on the sea can exist even without wind, these are tsunamis caused by natural disasters like underwater volcanic eruptions, and a wave that sailors call a coast. It is formed at sea after a strong storm, when the wind died down, but due to the large mass of water that came into motion from the wind and a phenomenon called resonance, the waves continue to sway. It should be noted that such waves are not much safer than a storm and can easily capsize a ship or boat with inexperienced sailors.
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 keep moving until they hit the ledges of the bottom near 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 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, which is played by giant storm waves in the open ocean, seems no larger 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 changes in 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 crests. 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 of the daily rotation of the 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 the relative position of the Earth, the Moon and the 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.
