Waves are created by the wind. Storms create winds that impact the surface of the water, resulting in ripples, just like the ripples in your cup of coffee after surfing when you blow on it. 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 impact on the surface of the water. Over time, the waves begin to increase in size. As the wind continues to blow and the waves it generates continue to be affected by it, the small waves begin to grow. The wind has a greater impact on them than on a calm water surface. The size of the wave depends on the speed of the wind that forms it. A wind blowing at a certain constant speed will be able to generate a wave of a certain size. And as soon as the wave reaches the maximum possible size for a given wind, it becomes “fully formed.” The generated waves have different speeds and wave periods. (See the section on wave terminology for more details.) Long period waves travel faster and travel longer distances than their slower counterparts. As they move away from the source of the wind (propagation), the waves form lines of surf (swells), which inevitably roll onto the shore. You are probably already familiar with the concept of “wave set”! Waves that are no longer affected by the wind that generated them are called groundwells. This is exactly what surfers are after! What affects the size of the surf (swell)? There are three main factors that influence the size of waves on the open sea: Wind speed - the higher it is, the larger the wave will be. The duration of the wind is similar to the previous one. Fetch (fetch, “coverage area”) - again, the larger the coverage area, the larger the wave is formed. As soon as the wind stops affecting them, the waves begin to lose their energy. They will move until the protrusions of the seabed or other obstacles in their path (a large island, for example) absorb all the energy. There are several factors that influence the size of the wave at a particular surf location. Among them: The direction of the surf (swell) - will it allow the swell to get to the place we need? Ocean bottom - a swell moving from the depths of the ocean to a reef, forms large waves with barrels inside. A shallow, long ledge extending toward the shore will slow down the waves and they will lose their energy. Tides - some sports are completely dependent on it. Find out more in the section on how the best waves appear

It seems like a trivial question, but there are some interesting nuances.

Waves arise for various reasons: due to wind, the passage of a ship, an object falling into the water, the gravity of the Moon, an earthquake, the eruption of an underwater volcano or a landslide. But if they are caused by the displacement of liquid from a passing ship or a falling object, the attraction of the Moon and the Sun contributes to the appearance of tidal waves, and an earthquake can cause a tsunami, with wind it is more difficult.

Here's how it happens...

Here the matter is in the movement of air - there are random vortices in it, small at the surface and large in the distance. As they pass over a body of water, the pressure decreases and a bulge forms on its surface. The wind begins to put more pressure on its windward slope, which leads to a pressure difference, and because of it, air movement begins to “pump” energy into the wave. In this case, the speed of the wave is proportional to its length, that is, the longer the length, the greater the speed. Wave height and wavelength are related. Therefore, when the wind accelerates a wave, its speed increases, therefore, its length and height increase. True, the closer the wave speed is to the wind speed, the less energy the wind can give to the wave. If their speeds are equal, the wind does not transfer energy to the wave at all.

Now let's figure out how waves are formed in general. Two physical mechanisms are responsible for their formation: gravity and surface tension. When some of the water rises, gravity tries to bring it back, and when it falls, it displaces neighboring particles, which also try to return back. The force of surface tension does not care in which direction the surface of the liquid is bent; it acts in any case. As a result, water particles oscillate like a pendulum. Neighboring areas are “infected” from them, and a surface traveling wave arises.

Wave energy is transmitted well only in the direction in which particles can move freely. This is easier to do on the surface than at depth. This is because the air does not create any restrictions, while at depth the water particles are in very cramped conditions. The reason is poor compressibility. Because of it, waves can travel long distances along the surface, but fade very quickly deep into the interior.

It is important that during the wave the liquid particles hardly move. At great depths, the trajectory of their movement has the shape of a circle, at shallow depths - an elongated horizontal ellipse. This allows ships in the harbour, birds or pieces of wood to bob on the waves without actually moving on the surface.

A special type of surface waves are the so-called rogue waves - giant single waves. Why they arise is still unknown. They are rare in nature and cannot be simulated in a laboratory setting. However, most scientists believe that rogue waves are formed due to a sharp decrease in pressure above the surface of the sea or ocean. But a more thorough study of them is ahead.

Here we are in detail

Let's talk about the Black Sea waves. Frequent recurrence of strong winds, significant sea sizes, great depths, and weakly rugged coastlines contribute to the development of waves. The highest wave heights in the Black Sea are 14 meters. The length of such waves is 200 meters. On the approaches to Sochi, the maximum wave height is 6 meters, length 120 meters.
You can evaluate excitement not only by wave elements (height, length, period), but also by degree.

The degree of excitement is assessed using a special scale. So, for example, on this scale, 1 point - wave height does not exceed 25 centimeters, 2 points - wave height 25-75 centimeters, 3 points - 0.75-1.25 meters, 4 points - 1.25-2 meters. The scale has 9 points in total. You can describe the state of the sea surface during wind waves: 1 point - the appearance of ripples during gusts of wind, 2 points - transparent glassy foam appears on the crests of the waves, 3 points - individual white “lambs” appear on the crests of the waves, 4 points - the entire sea is covered with “lambs” "etc.

The wind force scale (where points correspond to meters per second) has 12 points. The strength of a storm is determined by the strength of the wind. Therefore, the expression “storm 10 points” will be correct, but the expression “storm 10 points” will be incorrect. In the Black Sea, the frequency of strong waves is low. During the stormiest year, waves of 6-9 points are not observed for more than 17 days.

A distinctive feature of the Black Sea waves is their “stability”. This is the so-called swell, which has a longer period of oscillation than a wind wave. Swell is waves observed in light or no wind ("dead swell"). However, the origin of these waves is related to wind activity. Waves formed in the storm zone, which is located at this time in the western part of the Black Sea, may arrive on the Caucasian coast of the sea. On the Caucasian coast, the winds can be weak and the waves can be large. This will be the swell. The existence of swell is associated with the concept of the “ninth wave”, which has long existed among our sailors, known to many from Aivazovsky’s painting. It cannot be said that the idea of ​​a ninth wave was completely without any basis. The fact is that swell waves, as a rule, come in groups, with the largest waves in the center of the group, and smaller waves at the edges. Some wave of a given group may indeed be much larger than the others, but it will be the third, fifth or ninth, and from which wave to start counting is unknown. Thus, one should not think at all that the ninth wave is the most terrible. By the way, among the ancient Greeks, every third shaft was considered the most dangerous, and among the Romans - every tenth.

Sailors tolerate swell easier than Azov or Caspian wind waves - “bumpiness” with a period of 3-5 seconds. However, the swell has the unpleasant feature that it produces a strong surf near the shore. The wave, almost imperceptible in the sea due to its slight steepness, hits the shore with enormous force.

Video of stormy sea on the Black Sea (Anapa)

Swimming in the sea during a storm is very dangerous. It is usually quite difficult to overcome the breakers zone and get into the open sea, where you can float relatively calmly, rising and falling as each wave passes. It is much more difficult for a tired person to get back to the shore through the barrier of crashing and foaming waves. Every now and then he is carried back to the sea. There were cases when even people who knew how to swim well drowned here. That is why warning signs are posted on city and resort beaches during a storm. It is appropriate to recall here that all animals, jellyfish, sea fleas and other organisms leave the dangerous surf zone before a storm, seagulls fly to the shore, but you can see how some people choose the time of the storm in order to demonstrate their “bravery” by swinging on waves.

The force of waves hitting the shores and structures is enormous. Near Sochi it exceeds 100 tons per square meter. Such impacts produce bursts several tens of meters high. The colossal energy of breaking waves is spent on crushing rocks and moving sediment. Without the influence of waves, river washouts would gradually roll down to depth, but the waves return them to the shore and force them to move along it. For example, along the Caucasian coast of the Black Sea there is a constant flow of sediment. From Tuapse to Pitsunda, waves move 30 - 35 thousand cubic meters of sediment per year.

Where there is a beach, the waves lose most of their energy. Where there is none, they destroy bedrock. During the Great Patriotic War, the erosion of the coast south of the port of Sochi reached 4 meters per year. Immediately after the end of the war, shore protection work began in this area, and coastal erosion stopped.

A railway runs along the Caucasian coast of the sea. Sanatoriums, theaters, sea terminals and residential buildings were built in the coastal zone. Therefore, the seashores must be protected from erosion. The best protection in this regard is the beach, where the waves break before reaching the shore. To secure the beaches, groins and underwater breakwaters are built. These structures prevent the movement of pebbles along the shore to other areas and their migration into the depths of the sea. This is how the beach grows.

Are there tsunami waves in the Black Sea caused by earthquakes, like we have in the Far East? There are tsunamis, but they are very weak. They are registered only by instruments and are not even felt by humans.

To what depth do ordinary waves travel? Already at a depth of 10 meters they are smaller than on the surface, and at a depth of 50 meters they are completely invisible. Maybe there is peace in the depths, which nothing disturbs? No, that's not true. There are their own, so-called internal waves. They differ from surface ones in their size (tens of meters in height and kilometers in length), and the reasons for their origin are different. They arise, as a rule, at the interface between two layers with different densities. Although they are not visible on the surface, submarines face great difficulties during such an “underwater storm.”

In this article we will talk about where waves come from and what they are like. After all, waves are a unique natural phenomenon that gives surfers a lot of emotions and sensations, forcing them to give up a lot. Surfing is about waves. And good surfing is impossible without knowledge of how waves are created, what affects their speed, strength and shape, as well as without understanding that each wave is different from the other.

Where do waves in the ocean come from?

It's all about the swell. If it weren't for the swell, there would be no waves. What is swell? Swell is wind energy transferred to waves. There are several types of swells, wind and bottom (groundswell, roll-up):

1. As the name suggests, a wind swell is formed due to wind. This type of swell occurs when the wind blows directly offshore (for example, during a storm) and creates a chop (chaotic disturbance on the surface of the ocean). Wind swells are not very suitable for surfing.
2. The swell, due to which surf waves are formed on the ocean shore, is called bottom swell. This is where the waves that surfers are interested in come from.

How does a swell originate?

Far away in the ocean, a storm with strong winds is raging. These winds begin to agitate the water. The stronger the wind, the larger the wave size. A certain wind speed corresponds to a very specific wave size. It works like a sail and allows the wind to accelerate itself and do more.

When the waves reach their maximum possible size, they begin traveling to distant shores in the direction the wind blows. After some time, the waves become similar to each other - the larger ones absorb the small ones, and the fast ones eat up the slow ones. The resulting group of waves of approximately the same size and power is called a swell. A swell can travel hundreds or even thousands of kilometers before reaching the coastline.

As the swell approaches shallower depths, the lower flows of water hit the bottom, slow down and have nowhere to go except to move upward, pushing out all the water above them. When water can no longer support its own weight, it begins to collapse. Actually, this is where the waves you can surf on come from.

1. Close-outs are closed along the entire length in entire sections. Not the best option for skating unless you are learning to ride in foam. When the size of the waves is more than 2 meters, then such waves can be dangerous. Closeouts can be recognized by the width of the wave peak, which can reach several meters.
2. Spilling waves they slowly approach the shore and, thanks to the slight slope of the bottom, slowly begin to break, without forming a sharp wall and pipe. These waves need to be tackled early and are more suitable for beginner surfers and longboarders.
3. Plunging waves. Fast, powerful, sharp waves that form a pipe. They occur when a swell encounters an obstacle in its path. For example, this could be a protruding reef or a rock slab. We are used to seeing such waves in surf photos and surf videos. Allows you to make passages in a pipe and airs (jumps). Dangerous for beginner surfers.

Types of surf spots

The nature of the wave is determined by the place where it arises, this place is called a surf spot. Surf spots are divided into several types.

1. Beach-break: a swell comes to a beach with a sandy bottom and the wave, colliding with a wash of sand at the bottom, begins to break. The peculiarity of beach breaks is that the peaks rise in places where sandy alluviums are formed, and their shape and position can change every day, depending on the wind, undercurrents, tidal movement and other factors.
   With the change in the shape and size of the alluvium, the characteristics of the waves also change, that is, the waves can be both sharp trumpeting and gentle. The sandy bottom is not particularly dangerous, so beach breaks are great for learning to surf. In Bali, beach breaks include the entire beach along Kuta, Legian and Seminyak, as well as Brava Beach, Eco Beach and others.
2. Reef-break.This type of surf spot is characterized by the presence of a reef at the bottom. The reef can be either coral reefs or a rocky bottom in the form of individual stones or entire slabs. The shape, power and wavelength depend on the shape of the reef on the ocean floor. On a spot with a reef break, you can always predict where the peak of the wave will arise. Reef breaks are much more dangerous than beach breaks due to the sharp reefs and rocks on the bottom.In Bali, most surf spots are reef breaks. Uluwatu, Balangan, Padang Padang, Batu Bolong and many others.
3. Point-break- this is when with Well collides with some kind of obstacle protruding from the shore. It could be a rock ridge, a cape, or a small peninsula. After the collision, the waves go around this obstacle and begin to break one after another. In such places, waves of the most regular shape arise, they go one after another, and can give you very, very long passages.An example of a point break in Bali is the Medewi spot.

Wind and amount of water

In addition to location and swell, wind and water height (high and low tides) also influence where surf waves come from.

Where do the waves for riding or “blown with the wind” come from?
The quality of the waves depends on the wind on the shore. The best wind for surfing is no wind. This is why surfers get up at 4 am or earlier to get to the spot before dawn, when the wind has not yet woken up and the water is still glassy.

If the wind does blow, the waves will not be damaged (and sometimes even better) if it is directed from the shore into the ocean. This wind is called offshore. Offshore keeps the waves from breaking, making them sharper.

The wind that blows from the ocean to the shore is called onshore. It breaks the waves, causing them to close prematurely, blowing away the peaks. Least preferred wind of all. A strong onshore can generally kill the entire gurney.

The wind can also blow along the coast, it is called crossshore. Here a lot depends on its strength and direction. Sometimes crossshore can slightly spoil the waves, and sometimes it can act as negatively as onshore.

Ebbs and flows
You can read about tides and how they affect waves in this article

Anatomy of a wave

There are several elements in the structure of a wave:
Wall (face/wall)- the section of the wave where the surfer spends most of his time.
Lip- falling crest of a wave.
Shoulder- a place where the wave gradually fades away.
Sole (trough)- the very bottom of the wave.
Pipe (tube/barrel)- a place where water surrounds the surfer on all sides.

Now you know where the waves come from, but theory is theory, and you can truly know the waves only in the process of surfing. The more you watch and ride waves, the better you will become at reading the ocean, which will allow you to catch more and more great waves. Now put the board under your arm and run! 🙂

People take many natural phenomena for granted. 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 occurrence 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, you need to remember that water is agitated and vibrates forcibly - as a result of physical impact. A pebble, a boat, or a hand touching it set the liquid mass in motion, creating vibrations of varying 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, the 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 8 meters and stretch almost a quarter of a kilometer in length.

Sometimes the force is so destructive that it hits the coastal strip, uproots umbrellas, showers and other beach buildings, and demolishes everything in its path. And this despite the fact that oscillations are formed several thousand kilometers from the coast.

All waves can be divided into 2 categories:

• wind;
• standing.

Wind

Wind ones, as the name suggests, are formed under the influence of wind. Its gusts sweep tangentially, pumping 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 ascents and descents. Their peaks are called ridges, and their bases are called soles.

Having found out why waves form on the sea, the question remains open: why do they make oscillatory movements up and down? The explanation is simple - the variability of the wind. It flies in quickly and impetuously, then subsides. The height of the ridge and the frequency of oscillations directly depend on its strength and power. If the speed of movement and the strength of air currents exceed the norm, a storm arises. Another reason is renewable energy.

Renewable Energy

Sometimes the sea is completely calm, but waves form. Why? Oceanographers and geographers attribute this phenomenon to renewable energy. Water vibrations are its source and ways to maintain the potential for a long time.

In life it looks something like this. The wind creates a certain amount of vibrations in a body of water. The energy of these vibrations will last for several hours. During this time, liquid formations cover distances of tens of kilometers and “moor” in areas where it is sunny, there is no wind, and the body of water is calm.

standing

Standing or single waves arise due to tremors on the ocean floor, characteristic of earthquakes, volcanic eruptions, and also due to a sharp change in atmospheric pressure.

This phenomenon is called seiche, which translates from French like "swinging". Seiches are typical for bays, bays 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 travel long distances without changing shape or losing energy hit the shore and break. Moreover, each surge has a different effect on the coastal strip. If it washes the shore, it is classified as constructive.

The destructive surge of water hits the coast with its might, destroying it, gradually washing away sand and pebbles from the beach strip. In this case, the natural phenomenon is classified as destructive.

Destruction comes in different destructive powers. Sometimes it is so powerful that it collapses slopes, splits cliffs, and separates rocks. Over time, even the hardest rocks erode. America's largest lighthouse was built at Cape Hatteras in 1870. Since then, the sea has moved almost 430 meters into the coast, washing away the coastal strip and beaches. This is just one of dozens of facts.

Tsunami is a type of destructive water formations characterized by great destructive power. Their speed reaches up to 1000 km/h. This is higher than that of a jet plane. At depth, the height of the tsunami crest is small, but near the shore they slow down, but increase in 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 goes down, and the other part rises in parallel. Vibrations of varying strengths are formed on the surface of the reservoir.

Abnormal killers

They are also known as wanderers, monsters, anomalous and more common in the oceans.

Even 30-40 years ago, sailors’ stories about anomalous fluctuations in water were considered fables, because eyewitness accounts did not fit into existing scientific theories and calculations. A height of 21 meters was considered the limit for oceanic and sea fluctuations.