What the waves depend on. There are several factors that affect the size of the wave at a particular surf location.

The surface of the seas and oceans is rarely calm: it is, as a rule, covered with waves, and the surf beats continuously on the coast.

An astonishing sight: the massive cargo ship, played by giant storm waves in the open ocean, seems no bigger than a nutshell. Disaster films abound in such pictures - a wave as high as a ten-story building.

Wave fluctuations of the sea surface occur during a storm, when a prolonged gusty wind combined with drops atmospheric pressure forms a complex chaotic wave field.

Traveling waves, boiling surf foam

Moving away from the cyclone that caused the storm, one can observe how the wave picture transforms, how the waves become more even and slender rows moving one after another in the same direction. These waves are called swell. The height of such waves (that is, the difference in levels between the highest and the 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 in height such waves can reach 25 m. Wave oscillations from such waves propagate to a depth of 150 m.

From the area of ​​formation, the swell waves spread very far, even with complete calm. For example, cyclones passing off the coast of Newfoundland cause waves that in three days reach the Bay of Biscay off the western coast of France - almost 3,000 km from their place of formation.

When approaching the shore, as the depth decreases, these waves change their appearance. When wave fluctuations 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 effective in areas where the seabed drops sharply off 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 phenomenon of a completely different nature. 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 tidal period 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 also participates 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 mutual disposition Earth, Moon and Sun, which changes throughout the month. When they are in the same line (which happens on a full moon and a 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 sea level positions here is about 19.6 m.

Voted Thanks!

You may be interested in:

GCD for environmental education of children 6-7 years old

with elements research activities

Theme: Where do the waves of the sea come from?

Purpose of GCD: continue to introduce children to the properties of air. Give children the concept of air movement. Give children the opportunity to resolve themselves problem situation in the process of research activities. Develop mental activity, observation. Continue to develop a cognitive interest in nature in children.

Methods and techniques: children's experimentation, play technique, conversation, method of modeling, problem situation.

Material: baths with water, paints, brushes for each child. Paper boats and a fan by the number of children. Observation diaries, pencils, "pirate map", a bag of "treasures" - shells, pebbles, etc.

GCD move:

Guys, let's play one very interesting game:

I will be an artist, and you will be paints. With your help, I will paint different pictures.

I decided to draw the sea. All the guys, except Sasha, stand next to each other and stretch your arms forward, you will be the sea, and Sasha will be a boat. In this painting of mine, a very calm sea is drawn, only a slight ripple runs along its surface. A boat is sailing on the sea: (children stand calmly, slightly wiggling their fingers, a child depicting a boat, "floats" past the children). Suddenly, very small waves appeared on the sea. Let's try to draw these waves. (Children perform light wave-like movements with the palms of their hands, a child - a boat floats on the sea, as if swaying on the waves). Now I decided to draw the sea during the storm. Show me what the sea will be like during a storm, what waves there will be. Paint this picture. (Children make vigorous wave-like movements with their hands, and the boat sails strongly swaying on the wave).

Well, you managed to draw a real sea storm.

What do you guys think, where do the waves come from on the sea? (Waves appear due to the wind).

Do you want to check if this is really so? (Yes).

Then let's become a scientist with you for a while and conduct several experiments that will help us find out exactly where the waves of the sea come from. Walk into our lab and take a seat at your desks.

(Children sit at tables on which there is equipment for conducting experiments).

In order to begin our experiments, we need the sea. Each of you will make your own sea. Take bowls and fill them with water from the bottles on your tables. Did everyone get the same sea? (Yes).

And how, with the help of the colors that you see on your tables, we can make your seas different? (Add paint to the water).

What will happen to the water then? (It will become colored.)

Let's try to do this. (Children color the water different colors paints)

Why did your water become colored? (Assumptions of children. If children find it difficult to answer, then recall previous experiments with water and lead them to the conclusion that water has no color and is colored in any color).

What are your seas like now? (The seas turned out to be of different colors).

Now you and I have a black, red, yellow, blue sea.

See if there are waves on your sea now? Or is the sea calm, serene? (No waves. The sea is calm, serene).

Now blow softly on your sea.

What happened to the sea? (Waves appeared).

Why did the waves appear? (Because we blew on the water).

That's all right. You blew on the sea, and from this the air began to move above the water, and it was this air that made the water move, and the waves turned out.

And, let's, as real scientists, try in a different way to test our assumption that it was from the movement of air on the sea that waves appeared?

To do this, take a paper fan and wave it in your face. What do you feel? (How the wind blows).

You felt the wind blowing, that is, how the air moves. Now wave your fan over your sea. What happened to the sea? (Waves appeared again).

Now do you know exactly where the waves came from? (Yes. We made the wind like a fan and made the air move over the sea. This made waves).

Do you think this experience confirms our swami's assumption that it is from the movement of air on the sea that waves appear or not? (Answers of children).

You know that all scientists record their observations made during experiments. And we will sketch our experiences in our diaries. (Make sketchy sketches of the experience).

You guys have done a very serious scientific work... We need to rest a little. Let's play. Stand next to your chairs. Repeat the words of the game after me and perform the movements with me.

The wind blows in the open

Drives the waves in the blue sea ... (hands are raised up, bends to the side);

Fish are hiding at the bottom -

Swimming in a storm isn't easy! (squat and imitate the movements of the swimmer with their hands)

And when the storm in the sea dies down,

The sun will rise in the sky - (stand on their toes, reach up with their hands to the "sun")

We are in our boat,

We will sail in the blue sea! (imitate the movements of a swimmer with their hands).

Look, guys, and there are small, paper boats on your tables. You can go on them, on any journey. Where do you want to sail? (Answers of children)

Ah, let's sail to the island where the pirates buried the treasure of the sea king? (Answers of children)

Then send your ships out to sea and sail. (Children lower their ships into the water, each in his own "sea").

But why are our ships standing still? Why aren't they moving? What should be done to make them swim? (Children make various assumptions: push with their hand, wave a fan so that the wind appears).

Let's try to quietly blow on the ship. What happened? (The ship swam).

Why did our boat sail, what made it move? (We blew air on the boat, and the air made the boat sail)

Right. But the boat sails very quietly. This will take us too long to sail to our treasure island. What to do? (Assumptions of children. During the discussion, lead the children to the assumption that they need to blow harder on the boat).

Let's try to blow harder on the boat. What happened? (Our boat sailed faster).

Why do you think the boat began to sail faster? (We blew harder on him).

This means that the stronger the air flow, the faster our boat sails.

So we sailed to our island. Let's put the ships on dry land.

Look guys, I have a pirate map of the island. On it, a cross marks the place where the treasures are buried.

(Children examine the map and determine the place in the group, which is marked with a cross on the map. They find treasures previously hidden by the teacher).

Look, and here is the treasure bag. Let's see what lies there. (They open the bag and take out various shells, sea stones, pearls, dried starfish, etc.)

Do you like the treasures of the sea king?

Then I propose next time to go on a journey across the sea and drop in on a visit to the sea king.

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 in which the wind is blowing.

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

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

The size of the wave depends on the speed of the wind that forms it. The wind blowing at some constant speed can generate a wave of comparable size. And as soon as the wave acquires the size that the wind can lay in it, it becomes "fully formed."

The generated waves have different wave velocities and periods. (More details in the article) Waves with a long period move faster and overcome long distances than their slower cousins. As they move away from the source of the wind (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!

Are waves that are no longer affected by the wind called ground swells? This is exactly what surfers are after!

What affects the size of the 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.
Duration of the wind- 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 effect of the wind on them ceases, the waves begin to lose their energy. They will move until the projections 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 bottom- A swell moving from the depths of the ocean onto an underwater ridge of rocks forms large waves with barrels inside. A shallow protrusion opposite - will slow down the waves and cause them to lose energy.
Tidal cycle- some sports completely depend on it.

Find out how the best waves come about.

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 a change in the seasons, and a change in the 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 are formed at sea.

Why do waves appear at sea

There are theories that waves in the seas and in the oceans are caused by pressure drops. However, these are often only the assumptions of people who are quickly trying to find an explanation for such a natural phenomenon. In reality, things are a little different.

Remember what makes the water “flutter”. This is a physical impact. Throwing something into the water, running your hand over it, hitting the water sharply, vibrations of different sizes and frequencies will certainly begin to go along it. Based on this, it can be understood that waves are the result of physical impact on the surface of the water.

However, why do large waves appear on the sea, coming to the shore from afar? Everything is to blame a natural phenomenon- 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 effect that pumps the 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 are oscillatory. However, the answer to this question is even simpler than the very nature of the waves. The fact is that the wind has a fickle physical effect on the surface of the water, because it is directed to it in gusts of different strength and power. This also affects the fact that the waves have different sizes and frequencies. 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 is the fact that water waves are an ideal source of renewable energy. The fact is that waves are capable of storing their potential for a very long time. That is, the wind that set the water into action, creating a certain amount of oscillations (waves), can be enough for the wave to continue its oscillation for a very long time, and the wave potential itself does not exhaust itself even after tens of kilometers from the point of origin of the wave.

That's all the answers to the questions about why there are waves at sea.

Wave(Wave, surge, sea) - formed due to the cohesion of particles of liquid and air; sliding along the smooth surface of the water, at first the air creates ripples, and only then, it acts on its inclined surfaces, gradually developing the excitement of the water mass. Experience has shown that water particles have no translational motion; only moves vertically. Sea waves are the movement of water on the sea surface that occurs at regular intervals.

The highest point of the wave is called comb or the top of the wave, and the lowest point is sole. Height the wave is called the distance from the crest to its base, and length it 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 wave height 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 water surface... Sometimes the waves that hit the coast can be generated thousands of kilometers from the coast. But there are many other factors in the occurrence of sea waves: these are the tidal 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 bodies of water can be of two types:

1) Wind created by the wind, taking on a steady character after the wind stops acting 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 you notice the effect of the same wind on the surface of a wheat field. The inconstancy of wind currents, 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, ebbs and currents, waves in do not move the masses of water. Waves go, but the water remains in place. A boat that sways on the waves does not float away with the wave. She will be able to move a little on the inclined, only thanks to the force of the earth's gravity. Particles of water in a wave move in rings. The further 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 huge distances without changing shape and practically without losing energy, long after the wind that caused them has died down. Breaking on the shore, the sea waves release huge energy accumulated during the journey. The force of the continuously breaking waves changes the shape of the coast in different ways. Overflowing and rolling waves wash up the shore and are therefore called constructive... The waves crashing onto the shore gradually erode it and wash away the beaches that protect it. Therefore they are called destructive.

Low, wide, rounded waves offshore 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. When approaching the coast, 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. The headlands are formed of harder rock and erode more slowly than adjacent coastal areas. Steep, high sea waves erode rocky cliffs at the base, forming niches. The cliffs collapse at times. The terrace smoothed by 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 widens cracks in the rock, forming caves. Arches are formed when waves erode the rock from both sides until they join in a gap. When the top of the arch falls into the sea, stone pillars... Their bases are eroded, and the pillars collapse, forming boulders. The pebbles and sand on the beach are the result of erosion.

Destructive waves gradually erode the coast and carry away sand and pebbles from sea beaches. By bringing down all the weight of their water and washed away material onto slopes and cliffs, the waves destroy their surface. They press water and air into every crack, every crevice, often with explosive energy, gradually splitting and weakening the rocks. Broken rock fragments are used for further destruction. Even the hardest rocks are gradually being destroyed and the land on the coast is altered by the waves. Waves can destroy Coast with astonishing rapidity. 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 washed away the beaches 426 meters inland.

Tsunami

Tsunami are waves of tremendous 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 below one meter, but when approaching the shore, they slow down and grow up to 30-50 meters before collapsing, flooding the shore and sweeping away everything in their path. 90% of all registered tsunamis are noted in the Pacific Ocean.

Most common reasons.

About 80% of tsunami origins are underwater earthquakes... During an earthquake under water, the bottom is mutually displaced vertically: part of the bottom goes down, and part rises. On the surface of the water, oscillatory movements occur along the vertical, striving 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 resolved, and warning services are guided by the magnitude of the earthquake. The strongest tsunamis are generated in subduction zones. Also, it is necessary for the underwater shock to enter into resonance with wave oscillations.

Landslides... Tsunamis of this type occur more often than was estimated in the twentieth century (about 7% of all tsunamis). Often times, an earthquake causes a landslide and it also generates a wave. On July 9, 1958, an earthquake in Alaska caused a landslide in Lituya Bay. Ice mass 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 underwater landslides occur much more often 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 about 5% of all tsunamis. Large underwater eruptions have the same effect as earthquakes. With strong volcanic explosions, not only waves from the explosion are formed, but water also fills cavities from erupted material or even a caldera, as a result of which long wave... A classic example is the tsunami that formed after the eruption of Krakatoa in 1883. Huge tsunamis from the Krakatoa 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 coast for a considerable distance and drainage 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 dangers, can 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, being, for example, in Japan, on the Indian Ocean coast of Indonesia, Kamchatka. In the case of teletsunami, the wave usually comes up without the water receding.
• Earthquake... The epicenter of an earthquake is usually in the ocean. On the coast, an earthquake is usually much weaker, and often not at all. In tsunamo-prone regions, there is a rule that if an earthquake is felt, it is better to go 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, formation of cracks in the solder.
• Huge thrusts at the edges stationary ice and reefs, the formation of crowds, currents.

Killer waves

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

Some 10-15 years ago, scientists considered the stories of sailors about gigantic killer waves that arise out of nowhere and sink ships, just marine folklore. Long time wandering waves were considered fiction, since they did not fit into any mathematical models for calculating the occurrence and their behavior that existed at that time, because waves with a height of more than 21 meters in the oceans of planet Earth cannot exist.

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

Historical evidence of "killer waves"

So, in 1933, the US Navy ship "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 rampart of incredible height suddenly crept up behind. At first, the ship was thrown into a deep abyss, and then lifted almost vertically up a mountain of foaming water. The crew, who were lucky enough to survive, recorded the wave height - 34 meters. She moved at a speed of 23 m / s, or 85 km / h. So far, this is considered the highest killer wave ever measured.

During World War II, in 1942, the Queen Mary liner carried 16 thousand American troops from New York to Great Britain (by the way, the 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! - it went down sharply," - recalled Dr. Norwal Carter, who was aboard the ill-fated ship. The ship heeled at an angle of 53 degrees - if the angle was at least three degrees more, death would be inevitable. The story of "Queen Mary" formed the basis of the Hollywood movie "Poseidon".

However, on January 1, 1995, at oil platform In the North Sea off the coast of Norway, the Dropner first recorded a wave of 25.6 meters in height, called the Dropner wave. The "Maximum Wave" project allowed a new look at the reasons for the death of dry-cargo vessels that transported containers and other important cargo. Further studies were recorded in three weeks throughout the globe more than 10 single giant waves, the height of which exceeded 20 meters. New project received the name Wave Atlas, which provides for the compilation of a worldwide map of observed monster waves and its subsequent processing and addition.

Causes of occurrence

There are several hypotheses about the causes of extreme waves. Many of them lack common sense. Most simple explanations are based on the analysis of a simple superposition of waves of different wavelengths. Estimates, however, show that the probability of extreme waves in such a scheme is too low. Another noteworthy hypothesis assumes the possibility of focusing wave energy in some structures of surface currents. These structures, however, are too specific for the energy focusing mechanism 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.

It is interesting that 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. Salient 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), and the heights drop sharply at the edges.

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