A well-known specialist in the study of sea waves, Professor L. F. Titov, drew attention to the fact that in “The Tale of the Fisherman and the Fish,” the great poet not only figuratively, but also very correctly, from the point of view of oceanography, described the developing sea waves: “The sea is slightly broke out... The blue sea became clouded... The blue sea was restless... The blue sea turned black... There was a black storm on the sea: So the angry waves swollen, And so they walk, and so they howl and howl.”
There is a special scale of sea surface conditions, according to which you can visually determine how many points there are at sea. The scale is valid only for wind waves.
So what is one point? This is a very weak disturbance, a ripple. The wind blew - it wrinkled the water surface, a gust passed - it was smooth again. What is two points? This is already a more noticeable wave. A characteristic sign of waves of two points is transparent glassy foam on the crests of the waves. At three points, white caps appear on the crests of individual waves; at four scores, the entire sea is already covered with caps. If the wind begins to tear off the foam from the crests of the waves - five points of excitement, and when this foam begins to stretch out in stripes along the slopes of the waves - six points... In total, the excitement scale contains nine points. You can also evaluate a storm by wave height.
So, for example, on this scale, when the sea state is one point, the wave height does not exceed 25 centimeters, two points - 25-75 centimeters, three points - 0.75-1.25 meters...
The wind force scale (where points correspond to meters per second) has twelve points. The strength of a storm is determined by the strength of the wind. Therefore, the expression “a storm of ten points” will be correct, but the expression “a storm of ten points” will be incorrect. In the Black Sea, the frequency of strong waves is low. During the stormiest year, waves of six to nine 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 the painting of the famous moraine artist Aivazovsky. 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, travel 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, it 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.
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 to the shore again through a barrier of collapsing and foaming waves. Every now and then he is carried back to the sea. There were cases when people drowned here, even those who knew how to swim well. This is why warning signs are posted on city and resort beaches during storms. 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 a storm in order to demonstrate their “bravery” by swinging on the 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 sediment movement. Without the influence of waves, river runoff 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 sediment per year.
Where there is a beach, the waves disappear most your energy. Where there is none, they destroy bedrock. During the Great Patriotic War 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. IN coastal zone sanatoriums, theaters, sea terminals and residential buildings were built. 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, which prevent the movement of pebbles along the coast to other areas and their movement into the depths of the sea. This is how the beach grows.
For a long time, groins and underwater breakwaters were considered examples of coastal protection structures. But in recent years, experts have come to the conclusion that artificial reefs, such as those in natural conditions exist off the coast of Australia, Cuba, and Vietnam. One such reef, 300 meters long, is already being tested on the Black Sea near Odessa.
Georgian coastal protection specialists have taken a different route: they maintain beaches using beach material brought from mountain quarries.
One of the currently poorly studied issues related to waves is the so-called draft.
The essence of this phenomenon lies in the fact that in many ports of the Black Sea (and in some other ports of the world), ships moored at the piers begin to move along them from time to time more or less periodically under the influence of some force. Sometimes these movements are so powerful that even the steel mooring ends cannot withstand and burst; sometimes the ship is forced to stop cargo operations and retreat to the roadstead. The tyagun can be observed both during strong waves and during complete calm.
There are several hypotheses about the origin of the draft. All of them define the draft as a consequence of the approach of a special kind of sea waves, invisible to the naked eye. These waves are called long-period waves because they have a much longer period of oscillation than ordinary visible waves.
When sea waves approach the shore, their structure, and therefore the pattern of the waves, changes. Scientists say that in the coastal zone the wave begins to “feel the bottom.” If the direction of the wave crests is not parallel to the shoreline, then the waves turn toward the shore: the part of the crest that goes over greater depths catches up with the other part that goes closer to the shore over shallower depths. This phenomenon is called wave refraction. It is expressed not only in a change in their direction, but also in the fact that the ridges change their shape. In some areas, for example in a bay, the waves “stretch” along its shores, so the wave height here is less than in the open sea. The ancient sailors knew this. The concentration of wave energy occurs in the capes, as wave crests approach from different directions.
The waves crash against the formidable rocks with a roar
And with white foam they make noise and run back...
As waves move through shallow water, their profile changes. The ridge becomes sharper, leans forward, and the trough lags behind, experiencing the influence of the bottom. At a depth approximately one and a half times greater than the height of the waves, they are destroyed. A surf forms. A breaking wave with hissing foam reaches far onto the shore. On sub-deep shores there is usually one line of wave breaking, while on flat shores the waves break several times as they move towards the shore.
IN Lately A new, so-called spectral, method for studying sea waves has been adopted. The word "spectrum" comes from the Latin word "spectrum", which means "vision". There is something bright and beautiful associated with this word in our minds. This name was given to it by Newton when he first decomposed ordinary, white light into its components - red, orange, etc. Now the spectral research method is widely used in science and technology - wherever it is possible to obtain the dependence of the energy of a process on frequency or wavelength.
To characterize different types of sea waves, their spectrum will be a good indicator. What do the spectra of sea waves look like? The spectrum of wind waves and the spectrum of swell differ from each other in width and shape. Wind waves have a wider spectrum; they cover a large range of frequencies. It can have waves with periods from 3 to 20 seconds. And the swell spectrum is narrower, that is, the swell waves differ little from each other in frequency, they are smoother. The shape of the spectra of these two types of waves is characteristic of all seas.
There are sometimes double-humped and multi-peaked spectra. They are registered when two or more wave systems with different directions, that is, there is mixed excitement.
This is how spectra help in studying sea waves. Now it is no longer enough to say how many points there are at sea, even knowing the height and length or period of the waves is not enough. You need to know what type of spectrum they have. Spectra allow you to explore and compare with each other different kinds waves, they bring order to “the most disorderly of all natural phenomena on Earth,” as the famous Soviet oceanographer N. N. Gorsky figuratively called sea waves.
The word "tsunami" in Japanese means big waves in the harbor. Indeed, they appear in harbors, bays, and generally in the coastal zone. In the open sea, a ship may not notice them, because their height is centimeters and their length is kilometers, that is, the waves are very flat.
In the Soviet Union, tsunamis are observed not only in Kamchatka or the Kuril Islands, but also in the Caspian and Black Seas, although here they do not reach such destructive power as the Pacific ones.
These waves occur during an underwater earthquake. A ship that finds itself above an earthquake zone feels a shock, as if it had hit an underwater rock. On some nautical charts rocks were laid in areas where the depths are measured in kilometers and measurements do not reveal any rises in the bottom.
Where do earthquakes come from in the Black Sea? After all, there are no active volcanoes nearby! But the fact is that earthquakes are not always associated with volcanic activity. Most often they arise as a result of ruptures earth's crust, which are formed in areas intermediate between sinking and rising regions. Usually the foci of earthquakes are concentrated in the same zones. In the Black Sea, such zones run parallel to the coasts near Crimea and the Caucasus. The most seismic areas of the Caucasus are Anapa and the surrounding area of Sochi. The depth of the foci of Black Sea earthquakes can be up to 40 kilometers.
There is an assumption that the cause of the death of the ancient Black Sea cities of Sevastopolis and Dioscuria was waves from underwater earthquakes - tsunamis. In Abkhaz legends there is a mention of this event: “A terrible blow shook the earth. The shore split open and the enraged sea swallowed up the city.”
Over the past centuries, such strong earthquakes have not been observed in the Caucasus. In Crimea, there were strong earthquakes (7-8 points on a 12-point scale) in 1927, their epicenters were located in the sea, south of Yalta. These earthquakes caused long (up to 100 kilometers) waves - tsunamis. Their speed was so great that after an hour and a half they reached the coast of Bulgaria, and to other coasts even earlier. But these waves were only detected by instruments and did not cause any damage.
On the Caucasian coast of the Black Sea, strong earthquakes - magnitude 6 - were observed in 1905 and 1966 (their epicenters lay in the sea near Anapa). These earthquakes also caused tsunamis that spread throughout the sea and were recorded by instruments.
Thus, tsunamis are also possible in the Black Sea, but due to the short extent of earthquake sources and their relatively small strength, they do not cause harm to the coasts.
It is interesting that some fish - inhabitants of great depths - appear on the surface of the water a few days or hours before an earthquake and usually die. But such cases were not observed in the Black Sea, where, as is known, fish do not live at great depths.
To what depth do ordinary (wind) waves propagate? Already at a depth of 10 meters they are smaller than on the surface, but sometimes they are felt there too. The movement of water near the bottom during a storm can be characterized by this example. The Chernomor underwater laboratory, which worked near Gelendzhik at a depth of 12.5 meters and had a negative buoyancy of 3 tons, was moved by a force 4 storm by 70 meters. Researchers from this laboratory found that fairly intense sand movements occur to a depth of 15-20 meters.
In the depths of the sea, at the interface between layers of water with different densities, so-called internal waves arise.
Experts believe that the action of these waves can explain the death of several submarines: American - “Thresher” in the North Atlantic in 1963 and “Scorpio” in 1968 near the Azores; French - “Minerva” in 1968 and “Eridis” in 1970 in the Mediterranean Sea. Several hundred people died in the process.
Although internal waves have been known for a long time, the reasons for their formation are not entirely clear. One of them is considered to be “ripples” in the mass of the current, which occurs when it passes over underwater ridges. Internal waves can be caused by strong storms and hurricanes on the surface of the water, tides, and earthquakes.
Internal waves, like surface waves, move, develop, live. They can reach such a height and steepness that they become unstable and topple over. At the same time, the properties of the water quickly level out, the jump in density disappears, and perhaps this capsizing caused the death of the submarines.
Recently, internal waves have been detected in images from space. It turns out that when shooting from such a long distance, these waves can be traced in the form of alternating dark and light stripes.
For a long time, waves only caused harm to people: they reduced the speed of ships, smashed them against coastal structures, and washed away the shores.
Many projects have been put forward to harness wave energy. Let's talk about some of them.
An installation designed by D. A. Avtonomov was tested on the Black Sea coast. It is based on filling a pool with water under the influence of hydraulic shock - the passage of waves through wedge-shaped channels. From the pool, water flows into the turbine.
Another installation was also tested on the Crimean coast, its author was S.I. Koltagov. A piston moving horizontally in a cylinder under the action of waves drives water up the pipe into a tank, from where it enters the turbine. After each movement of the piston, the cylinder is filled from another pipe with sea water.
Engineer V.S. Sidorenko created a type of “wave turbine” based on the rotation of a horizontally reinforced pipe as a wave passes.
Polish experts proposed storing energy by periodically (under the influence of waves) supplying water to a reservoir located above the water level. The impact of each wave opens a valve through which water flows through the pipes into the tank.
The Bulgarian engineer Vedenicharov proposed seven types of wave motors. He tested some of them on the Black Sea near Varna.
Swedish engineer Dahlstrom designed a ship that uses wave energy. The ship has a balancer that drives the propeller.
A wave energy buoy operates off the coast of the United States; the installation power is only 1 kilowatt. The operating principle is as follows: a 60-meter pipe is lowered from the floating platform; at the bottom of the pipe there is a valve that opens when the pipe is in the wave trough; The water entering the pipe enters the tank, and from the tank to a turbine, which generates a current that powers the lamp.
A major project for the use of wave energy has been put forward in England, which does not have significant natural energy sources on its territory. It is planned to build many unique “mills” along the coast, the blades of which (15X15 meters) will rotate under the influence of waves and transmit their movement to the generator.
No country has yet built a wave power plant. The reason is that the energy obtained in this way will cost more than the energy of other types of power plants, and it is advisable to use it only where all other sources have already been exhausted.
However, the very fact that engineers and scientists in many countries are working hard on the use of wave energy allows us to hope for a successful solution to this problem.
Doctors also became interested in sea waves: weak waves (one or two points) produce a light massage of the body, promote the penetration of sea water salts into the human body, that is, it is a healing factor.
No less interesting is this question: does the Sun influence marine processes? Observations of the course of various terrestrial phenomena make it possible to note not only their periodicity, but also the coincidence of periods of oscillations of these processes with periods of changes in solar activity.
What kind of phenomena on Earth have they tried to compare with the activity of the Sun: disruption of the rhythms of development of animals and plants, a decrease in reactions in people during periods of active Sun and an increase in the number of deaths among people suffering from diseases of the cardiovascular system, a slowdown in the growth of glaciers, and even the number of earthquakes , according to some scientists, is associated with the degree of solar activity.
How are things going in such a small area of the planet as the Black Sea? Analysis of “quiet” and “stormy” years shows that they follow each other in a certain order. Thus, for the Sochi region in 1952-1954 and 1964-1966 there were many storms, and 1956-1962 were years of calm. Of course, even in quiet years there are occasional strong storms. For example, in the quiet year of 1968, there was an exceptionally strong storm on January 28-29, and in the quiet year of 1969, force 7 storms were observed on January 5-6 and October 28-29.
The entire year of 1972 can be called stormy. The strength of the storm near the coast reached 6-7 points.
Over the past 15 years, storm activity has gradually subsided, but the onset of a storm period is just around the corner, as it was before.
If we compare the number of storms in the Black Sea with the number of flares on the Sun, we can see that there is a relationship between them.
Almost always, a major solar flare is followed by a storm. But not every storm is caused by a solar flare. There are many more storms than flashes, but each strong flash causes a storm. During the period of disturbance, the Sun emits streams of charged particles - corpuscles, and the so-called “solar wind” begins. It is still unclear in what way these flows influence the Earth’s atmosphere; the increase in movement is especially noticeable. air masses along the meridians - from north to south and from south to north. On the Black Sea this means the arrival southern cyclones and storms from the south.
Astronomers are trying to predict solar flares. First of all, this is necessary so that astronauts in flight take the necessary measures to protect themselves from cosmic rays, which erupt from the flare area along with streams of light, ultraviolet, gamma radiation, infrared and radio radiation.
Once such forecasts are established, they can be used for medical purposes, as well as for forecasting storms.
If it were possible to predict calm and stormy years, this would greatly facilitate the work of ports and secure shipping.
Marine site Russia no November 23, 2016 Created: November 23, 2016 Updated: November 23, 2016 Views: 5195
As was said, in individual seas and oceans, in addition to general characteristics, there are also so-called special ones, characteristic of a specific geographical area.
For other areas not included in the book, special signs must be found in various navigation aids (pilots, etc.) and hydrometeorological descriptions, and you also need to thoroughly study the navigation area yourself and notice special weather signs in it.
Black Sea
Among the winds, Novorossiysk Bora 1 stands out as particularly famous. It is the most dangerous type of storm for the fleet in the northeast of the Black Sea, especially in the area of the coast of Anapa - Novorossiysk - Tuapse. Novorossiysk bora - This is a very strong cold north-east gusty wind blowing from low mountain slopes. Its greatest strength is observed in Tsemes (Novorossiysk) Bay. Here the strongly cooled continent drops steeply to the warm sea.
This storm occurs during an anticyclone in cold air over the southern regions of European territory Soviet Union and during a cyclone - over the southeastern part of the Black Sea.
At the same time, large horizontal pressure gradients are created, as a result of which the air rushes in huge gusts through the Markhot Pass from a height of 435 m into the Novorossiysk Bay with the speed of a hurricane wind, which causes strong rough seas with a very steep wave and, at subzero temperatures, creates powerful icing of ships and ports. construction. There were cases when ships sank in the bay under the weight of the ice that formed on them.
On average, the Novorossiysk bora is observed 46 times a year, most often in the period from November to March. Of these, more than half occur with wind speeds above 20 m/sec.
The highest wind speed reaches 40 m/sec or more, while the air temperature can drop to minus 15 - 18° and below. The boron continues continuously for 1 - 3 days, sometimes up to a week. Its spread towards the sea does not exceed 5 - 6 miles.
Local signs of the onset, weakening and cessation of the Novorossiysk bora are as follows:
The appearance of a whitish cloud bank over the Varada ridge and its sliding down the mountain slopes towards the sea. Bora begins when the cloud bank descends approximately halfway down the mountain slope.
If cloud masses have broken away from the Markhot Pass and are quickly moving in a southwestern direction, this is a sign that bora in Novorossiysk will begin in 2-3 hours or even earlier.
A sharp weakening in the north of the eastern wind in Novorossiysk with a strong one at the Markhot Pass, as evidenced by the cloud bank on the mountain slope remaining almost in the same position, does not indicate the end of the bora; The wind will pick up again in 2 - 3 hours.
The strengthening of the northeast wind in Novorossiysk to 6 - 7 points and even more, while the wind remains weak at the Markhot Pass, indicates that there will soon be no wind in Novorossiysk.
If low-level cloudiness advances and increases from the south, accompanied by precipitation and a drop in pressure, then the bora will stop in 8 - 12 hours.
The rapid increase in pressure in Novorossiysk is a sign of the beginning of weakening and the imminent cessation of the bora here.
In the area of the Poti coast, during the cold period of the year (from October to March), a very strong foehn easterly wind is often observed, sometimes reaching hurricane force, with a speed of up to 40 m/sec and a duration of up to several days.
This wind is observed from the Supsa River to the Inguri River, at sea it extends up to 10 miles from the coast. The local name for this wind is Potisky kalach or round timber.
Signs of the occurrence of a stormy east wind in the Poti area are as follows: atmospheric pressure is above 1015 mbar with a uniform drop, a significant increase in air temperature and a decrease relative humidity, the appearance of cirrus and lenticular clouds over the mountains, ultra-long visibility of distant mountains, the disappearance of low clouds.
Usually this wind intensifies in the second half of the night and subsides in the middle of the day, and in the evening it can intensify again. Squalls are also often observed in the Poti area. westerly winds, most often southwestern and western, less often northwestern.
The signs of their occurrence are as follows:
the appearance of cirrus clouds over the coast during a fen and their gradual compaction with the formation of middle-tier clouds is a sign that in the next 6 - 10 hours squally westerly winds will arise here and cloudy weather with precipitation will set in;
the appearance of swells in the sea in clear weather, especially during the foehn;
ultra-long visibility of mountains;
the strengthening of sea currents in the Poti area to one knot or more is a sign of the strengthening of the western wind here to a storm in 18 - 24 hours; a sign of the strengthening of this wind after a few hours (3 - 4 hours) is a noticeable increase in the water level in Poti.
In April and May it is abnormal high temperature, low relative humidity (dryness) of the air and a drop in pressure, we should expect a sudden strong squall from the southwest in a few hours.
Poti and Transcaucasia is an increase in pressure, a decrease in cloudiness and sea swell.
In the areas of capes Tarkhankut, Sarych, Sudan, Kaliakra, Anapa and in the Kerch Strait with a noticeable change atmospheric pressure There is a local intensification of weak and moderate winds to strong and stormy ones: the southern wind - three drops in pressure, the northern - with an increase. When the pressure in these areas changes by 1 - 2 mbar, the winds can increase to 6 - 7 points.
The strengthening extends from the coast to the sea up to 5 - 6 miles, then the winds weaken sharply.
In the Black Sea basin, strong and prolonged storms from the directions of the northern half of the horizon are observed in winter. They are preceded and accompanied by a sharp drop in temperature and air pressure, snowfall, the formation of fog, and evaporation. Wind speed reaches 25 - 40 m/sec.
Storms from southerly winds on the Black Sea are observed much less frequently, and they are usually less strong and shorter lasting than with northerly winds. Before the onset of a southern storm, ultra-long visibility may be observed a day or more in advance: the mountains of the Anatolian coast can be visible from South Bank Crimea.
Bosphorus
White clouds forming over the peaks of the European shore of the strait are a sign imminent arrival northwestern storm winds. At the same time, if the clouds begin to slide down the mountain slope towards the strait, then strong northwestern squalls, often accompanied by thunderstorms, will soon appear.
Aegean Sea
During the cold season (from October to March), if the mountains on the islands are hidden by gray clouds and the sky is covered with low clouds, then a strong wind will soon blow.
If the sky is covered with clouds approaching from the southwest, the pressure drops, and thunderstorms are observed, then during the cold period of the year you should expect a southwest storm.
Before the onset of a northern storm with squalls, the pressure increases noticeably and clear weather sets in with good visibility.
Bay of Biscay
Storms are very common in the Bay of Biscay. They are usually observed from October to March and especially from November to February.
They are usually accompanied by rainy and stormy weather and very strong and dangerous waves for ships.
Storms in the Bay of Biscay are associated with the passage of cyclones, which most often have two trajectories: northeast and east-southeast. From June to August, thunderstorms are observed here, which in the southern part of the bay are accompanied by strong squalls.
Signs of the onset of storms in the Gulf are low, gloomy clouds moving in from the west, often with lightning, and a dead swell coming from the west.
Off the southern coast of the bay, a dead swell coupled with calm weather following southwesterly winds is also a sure sign of an approaching storm.
It is also characteristic that the longer the above signs are observed before the onset of the storm, the stronger and longer the storm itself will be.
Usually arising from the southwest, the storm, accompanied by precipitation and fog, gradually turns west or northwest and can last up to several days in a row. Then the wind returns to its original direction.
If, at the end of the storm, strong winds blow from the southwest, accompanied by an increase in pressure, then we can expect a northerly wind and improved weather.
If a reversal of the wind from the northwest to the west or southwest is accompanied by a significant drop in pressure, then we should expect the imminent onset of a new storm.
Red Sea, Gulf of Aden and Suez
In the northern part of the Red Sea and in the Gulf of Suez, the appearance of cirrus clouds over the peaks of the mountains of the Sinai Peninsula, at a time when they are visible from the southern entrance to the Gubal Strait, is a sign of the imminent occurrence of strong to gale force winds. In the same areas, a sign of the imminent appearance of fresh wind is haze on the horizon. In the Gulf of Suez, if haze covers the plateaus, it is a sign of the imminent onset of a big storm.
The appearance of a dry strong north wind (khamsin) in the Gulf of Aden is preceded by heavy rainfall in Yemen. Near the northern shore of the Gulf of Aden, a sign of the onset of strong winds from the north and north-northwest “belat” is the appearance in the evening of a dim foggy arc over the shore and a gusty wind gradually approaching the shore.
In the Gulf of Aden, signs of an approaching cyclone from the east and south are a halo around the moon and sun, lightning on the eastern horizon, squalls from the north-northwest and north-northeast, a dead swell coming from the east, and a drop in pressure.
Port of Cape Town
If the top of Mount Leo is covered with a white cloud cap, it is a sign of the imminent onset of a strong storm.
Port of Petropavlovsk-Kamchatsky. Avacha Bay
Signs of the north-west wind strengthening to a storm are the following: the formation of a cloud cap over the Vilyuchinskaya Sopka, the presence of a sharply defined cloud ridge of cumulus-shaped clouds over the western part of the bay.
Mediterranean Sea
A change in wind direction during a storm from east to west is a sure sign of improving weather. Eastern winds stormy weather is usually predicted here.
White Sea
If a south wind begins to blow on the White Sea, it is a sign of the imminent onset of inclement weather.
Hebrides and coast of Scotland
North gale wind changing direction to southwestern when atmospheric pressure drops, this is a sure sign of further deterioration of the weather.
Newfoundland Island
If after a westerly wind the atmospheric pressure begins to fall slowly, then a prolonged eastern storm should be expected.
Scottish and Orkney Islands
Strong aurora is a sign of the onset of a southeast storm, and weak aurora is a sign of the onset of good weather.
Gulf of Bothnia
A rapid drop in atmospheric pressure, as well as clouding of the sky with thick stratus clouds, are a sign of the approach of a cyclone and often stormy winds.
Coast of Celebes Island
On the northern coast of the island, especially in the area of Manado Bay, during the northwest monsoon, stormy westerly winds, locally called “barat,” are observed. A sign of the approach of a barat is the dark, leaden color of the sky over the sea. The air temperature usually drops to 19° C instead of the usual 25 - 27° C.
Strait of Magellan
A white arc of clouds visible in the southwest is a sure sign of a strong storm squall approaching from Cape Horn.
Straits of Florida
Often in this area there is a gale with strong squalls, which is locally called “porter”. A sign of the onset of this wind is a drop in atmospheric pressure and the approach of powerful cumulus clouds from the northwest with a weak southeast wind.
Arctic Ocean
Jets of snow turning into drifting snow when the wind picks up are a sign of a blizzard beginning. At the same time, as the wind strengthens, the snow it carries rises higher and higher, the horizon is gradually covered with a snowy haze and visibility deteriorates sharply.
The coast of Antarctica in the area of the Atlantic sector With strong winds from the eastern quarter, a low-level snowstorm usually begins, which then turns into a general snowstorm; Visibility becomes very poor.
The following phenomena can serve as signs of a stormy wind in the eastern quarter:
the appearance and compaction of cirrostratus clouds;
an increase in air temperature during the polar night, as well as in summer, spring and autumn in the evening and at night;
a significant increase in relative air humidity;
very strong drop in atmospheric pressure.
Atlantic sector of Antarctic waters
The following phenomena can serve as signs of increased wind in the open part of the ocean:
1) the wind turns to the right and the pressure transitions from level to falling while the air temperature rises, cloudiness thickens and decreases, and precipitation begins. These phenomena are associated with the approach of a cyclone to the ship’s location and, as a rule, foreshadow northern quarter winds (from northwestern to northeastern) with a force of 6 - 8 points or more;
2) an increase in pressure, starting after a noticeable drop and accompanied by a change in wind direction from south to southwest. At the same time, precipitation usually stops and visibility improves.
The intensity of an approaching storm can be judged by the barograph record: the steeper the pressure rises, the more likely a strong storm (up to a hurricane) is likely, which usually begins soon after the pressure begins to rise.
The second sign, if clearly expressed, is characteristic of the rear part of the cyclone, provided that its center passes north of the ship.
Storms with northerly winds often precede southwesterly storms. It should be borne in mind that in Antarctica there is not such a strict relationship between changes in atmospheric pressure and wind as is observed in the northern hemisphere.
There may be cases of strong storms with small pressure fluctuations and, conversely, often significant changes in pressure are not associated with strong wind.
Therefore, in Antarctica, in addition to pressure changes, it is necessary to take into account changes in wind, temperature, cloudiness and other meteorological phenomena, as well as the direction and time of the appearance or intensification of the swell.
The wind changes during the passage of a cyclone as follows:
if the ship is located directly in the central part of the cyclone, then at first a strong north-northeast wind blows, which, after the center shifts, quickly changes to south-southwest;
when the center of the cyclone passes south of the ship, a north wind is initially observed, which then turns to the north-west and intensifies, and after the center of the cyclone shifts, it changes to the south-west with an increase in pressure and a strong storm.
In the event that the ship is located in an area of strong westerly winds, which is located between 40 and 55° south. sh., the wind varies from north-west to south-west; if the center of the cyclone passes north of the ship, the wind starts from the north, passes through the northeast to the east and, after the cyclone moves, to the southeast and south.
For the vast majority of cyclone trajectories, the passage of their centers south of the ship is observed in those cases when the ship is north of the 61st parallel. The movement of the center of the cyclone through the vessel's position is most likely when sailing in the area between 61 and 65° south. w.
Finally, the movement of the cyclone center north of the ship is observed when sailing south of the Arctic Circle. Sometimes for individual trajectories of cyclone centers, their paths can deviate significantly from the above average position.
Wind- this is horizontal movement (air flow parallel to the earth's surface) resulting from uneven distribution heat and atmospheric pressure and directed out of the zone high pressure to the low pressure zone
Wind is characterized by speed (strength) and direction. Direction is determined by the sides of the horizon from which it blows, and is measured in degrees. Wind speed measured in meters per second and kilometers per hour. Wind strength is measured in points.
Wind in boots, m/s, km/h
Beaufort scale- a conventional scale for visual assessment and recording of wind force (speed) in points. Initially, it was developed by the English admiral Francis Beaufort in 1806 to determine the strength of the wind by the nature of its manifestation at sea. Since 1874, this classification has been adopted for widespread (on land and at sea) use in international synoptic practice. In subsequent years it changed and was refined (Table 2). A state of complete calm at sea was taken as zero points. Initially, the system was thirteen-point (0-12 bft, on the Beaufort scale). In 1946 the scale was increased to seventeen (0-17). The wind strength on the scale is determined by the interaction of the wind with various items. In recent years, wind strength is more often assessed by speed, measured in meters per second - at the earth's surface, at a height of about 10m above the open, flat surface.
The table shows Beaufort scale, adopted in 1963 by the World Meteorological Organization. The sea wave scale is nine-point (parameters are given for a large sea area; in small water areas the waves are less). Descriptions of the effects of the movement of air masses are given “for the conditions of the earth’s atmosphere near the earth’s or water surface,” and above-zero temperatures. On the planet Mars, for example, the ratios will be different.
Wind strength in Beaufort scale and sea waves
Table 1
| Points | Verbal indication of wind force | Wind speed, m/s | Wind speed km/h | Wind action |
|
on the land |
at sea (points, waves, characteristics, height and wavelength) |
||||
| 0 | Calm | 0-0,2 | Less than 1 | Complete absence of wind. The smoke rises vertically, the leaves of the trees are motionless. | 0. No excitement
Mirror smooth sea |
| 1 | Quiet | 0,3-1,5 | 2-5 | The smoke deviates slightly from the vertical direction, the leaves of the trees are motionless | 1. Weak excitement.
There are light ripples on the sea, no foam on the ridges. Wave height is 0.1 m, length - 0.3 m. |
| 2 | Easy | 1,6-3,3 | 6-11 | You can feel the wind on your face, the leaves rustle faintly at times, the weather vane begins to move, | 2. Low excitement
The ridges do not tip over and appear glassy. At sea, short waves are 0.3 m high and 1-2 m long. |
| 3 | Weak | 3,4-5,4 | 12-19 | Leaves and thin branches of trees with foliage continuously sway, light flags sway. The smoke seems to be licked from the top of the pipe (at a speed of more than 4 m/sec). | 3. Slight excitement
Short, well defined waves. The ridges, overturning, form a glassy foam, and occasionally small white lambs are formed. Average height waves 0.6-1 m, length - 6 m. |
| 4 | Moderate | 5,5-7,9 | 20-28 | The wind raises dust and pieces of paper. Thin branches of trees sway without leaves. The smoke mixes in the air, losing its shape. This is the best wind for operating a conventional wind generator (with a wind wheel diameter of 3-6 m) | 4.Moderate excitement
The waves are elongated, white caps are visible in many places. Wave height is 1-1.5 m, length - 15 m. Sufficient wind thrust for windsurfing (on a board under sail), with the ability to enter planing mode (with a wind of at least 6-7 m/s) |
| 5 | Fresh | 8,0-10,7 | 29-38 | Branches and thin tree trunks sway, the wind can be felt by hand. Pulls out big flags. Whistling in my ears. | 4. Rough seas
The waves are well developed in length, but not very large; white caps are visible everywhere (in some cases, splashes form). Wave height 1.5-2 m, length - 30 m |
| 6 | Strong | 10,8-13,8 | 39-49 | Thick tree branches sway, thin trees bend, telegraph wires hum, umbrellas are difficult to use | 5. Major disturbance
Large waves begin to form. White foamy ridges occupy large areas. Water dust is formed. Wave height - 2-3 m, length - 50 m |
| 7 | Strong | 13,9-17,1 | 50-61 | Tree trunks sway, large branches bend, it is difficult to walk against the wind. | 6. Strong excitement
The waves pile up, the crests break off, the foam lies in stripes in the wind. Wave height up to 3-5 m, length - 70 m |
| 8 | Very strong |
17,2-20,7 | 62-74 | Thin and dry branches of trees break, it is impossible to speak in the wind, it is very difficult to walk against the wind. | 7. Very strong excitement
Moderately high, long waves. Spray begins to fly up along the edges of the ridges. Strips of foam lie in rows in the direction of the wind. Wave height 5-7 m, length - 100 m |
| 9 | Storm | 20,8-24,4 | 75-88 | Big trees bend, big branches break. The wind tears tiles off the roofs | 8.Very strong excitement
High waves. The foam falls in wide dense stripes in the wind. The crests of the waves begin to capsize and crumble into spray, which impairs visibility. Wave height - 7-8 m, length - 150 m |
| 10 | Strong storm |
24,5-28,4 | 89-102 | Rarely happens on land. Significant destruction of buildings, wind knocks down trees and uproots them | 8.Very strong excitement
Very high waves with long, downward-curving crests. The resulting foam is blown away by the wind in large flakes in the form of thick white stripes. The surface of the sea is white with foam. The strong roar of the waves is like blows. Visibility is poor. Height - 8-11 m, length - 200 m |
| 11 | Cruel storm |
28,5-32,6 | 103-117 | It is observed very rarely. Accompanied by great destruction over large areas. | 9. Exceptionally high waves.
Small and medium-sized vessels are sometimes hidden from view. The sea is all covered with long white flakes of foam, located downwind. The edges of the waves are blown into foam everywhere. Visibility is poor. Height - 11m, length 250m |
| 12 | Hurricane | >32,6 | More than 117 | Devastating destruction. Individual wind gusts reach speeds of 50-60 m.s. A hurricane may occur before a severe thunderstorm | 9. Exceptional excitement
The air is filled with foam and spray. The sea is all covered with stripes of foam. Very poor visibility. Wave height >11m, length - 300m. |
To make it easier to remember(compiled by: website author)
3 - Weak - 5 m/s (~20 km/h) - leaves and thin tree branches sway continuously
5 - Fresh - 10 m/s (~35 km/h) - pulls out large flags, whistles in ears
7 - Strong - 15 m/s (~55 km/h) - telegraph wires are humming, it is difficult to go against the wind
9 - Storm - 25 m/s (90 km/h) - wind knocks down trees, destroys buildings
* Surface wind wavelength water bodies(rivers, seas, etc.) - the smallest horizontal distance between the tops of adjacent ridges.
Dictionary:
Breeze– weak onshore wind, with force up to 4 points.
Normal wind- acceptable, optimal for something. For example, for sport windsurfing, you need sufficient wind thrust (at least 6-7 meters per second), and for parachute jumping, on the contrary, it is better to have calm weather (excluding lateral drift, strong gusts near the earth's surface and dragging of the canopy after landing).
Storm is called a long-lasting and stormy wind to a hurricane, with a force greater than 9 points (gradation on the Beaufort scale), accompanied by destruction on land and strong waves at sea (storm). Storms are: 1) squalls; 2) dusty (sandy); 3) dust-free; 4) snowy. Squalls begin suddenly and end just as quickly. Their actions are characterized by enormous destructive power (such wind destroys buildings and uproots trees). These storms are possible everywhere in the European part of Russia, both at sea and on land. In Russia, the northern border of the distribution of dust storms passes through Saratov, Samara, Ufa, Orenburg and the Altai mountains. Snow storms of great force occur on the plains of the European part and in the steppe part of Siberia. Storms are usually caused by the passage of an active atmospheric front, deep cyclone or tornado.
Squall- a strong and sharp gust of wind (Peak gusts) with a speed of 12 m/sec and above, usually accompanied by a thunderstorm. At a speed of more than 18-20 meters per second, gusty wind demolishes poorly secured structures, signs, and can break billboards and tree branches, cause power lines to break, which creates a danger for people and cars nearby. Gusty, squally wind occurs during the passage of an atmospheric front and with a rapid change in pressure in the baric system.
Vortex – atmospheric education with rotational movement of air around a vertical or inclined axis.
Hurricane(typhoon) is a wind of destructive force and considerable duration, the speed of which exceeds 120 km/h. A hurricane “lives,” that is, moves, usually for 9–12 days. Forecasters give it a name. The hurricane destroys buildings, uproots trees, demolishes light structures, breaks wires, and damages bridges and roads. Its destructive power can be compared to an earthquake. The homeland of hurricanes is the ocean, closer to the equator. Cyclones saturated with water vapor move from here to the west, more and more twisting and increasing speed. The diameters of these giant vortices are several hundred kilometers. Hurricanes are most active in August and September.
In Russia, hurricanes most often occur in the Primorsky and Khabarovsk territories, Sakhalin, Kamchatka, Chukotka, and the Kuril Islands.
Tornadoes– these are vertical vortices; squalls are often horizontal, part of the structure of cyclones.
The word "smerch" is Russian, and comes from the semantic concept of "twilight", that is, a gloomy, stormy situation. A tornado is a giant rotating funnel, inside of which there is low pressure, and any objects that are in the path of the tornado's movement are sucked into this funnel. As he approaches, a deafening roar is heard. A tornado moves above the ground at an average speed of 50–60 km/h. Tornadoes are short-lived. Some of them “live” for seconds or minutes, and only a few - up to half an hour.
On the North American continent, a tornado is called tornado, and in Europe – thrombus. A tornado can lift a car into the air, uproot trees, bend a bridge, and destroy the upper floors of buildings.
The tornado in Bangladesh, observed in 1989, was included in the Guinness Book of Records as the most terrible and destructive in the entire history of observations. Despite the fact that residents of the city of Shaturia were warned in advance about the approach of the tornado, 1,300 people became its victims.
In Russia, tornadoes occur more often in summer months in the Urals, Black Sea coast, in the Volga region and Siberia.
Forecasters classify hurricanes, storms and tornadoes as emergency events with a moderate speed of spread, so most often it is possible to announce them in time a storm warning. It can be transmitted through civil defense channels: after the sound of sirens " Attention everyone!"You need to listen to local television and radio reports.
Symbols on weather maps for wind-related weather events
In meteorology and hydrometeorology, the direction of the wind (“from where it blows”) is indicated on the map as an arrow, the type of plumage of which shows the average speed of air flow. In air navigation, the name of the direction is the opposite. In navigation on water, the unit of speed (knot) of the vessel is taken to be equal to one nautical mile per hour (ten knots correspond to approximately five meters per second).
On a weather map, a long feather of a wind arrow means 5 m/s, a short one - 2.5 m/s, in the shape of a triangular flag - 25 m/s (follows a combination of four long lines and 1 short one). In the example shown in the figure, there is a wind of 7-8 m/s. If the wind direction is unstable, a cross is placed at the end of the arrow.
The picture shows the symbols of wind direction and speed used on weather maps, as well as an example of applying icons and fragments from a hundred-cell matrix of weather symbols (for example, drifting snow and a blowing snow, when previously fallen snow rises and is redistributed in the ground layer of air).
These symbols can be seen on the synoptic map of the Hydrometeorological Center of Russia (http://meteoinfo.ru), compiled as a result of analysis of current data on the territory of Europe and Asia, which schematically shows the boundaries of zones of warm and cold atmospheric fronts and the directions of their movements along the earth's surface.
What to do if there is a storm warning?
1. Close and secure all doors and windows tightly. Apply strips of plaster crosswise to the glass (to prevent fragments from scattering).
2. Prepare a supply of water and food, medicine, a flashlight, candles, a kerosene lamp, a battery-powered receiver, documents and money.
3. Turn off gas and electricity.
4. Remove items from balconies (yards) that could be blown away by the wind.
5. Move from light buildings to stronger ones or civil defense shelters.
6. In a village house, move to the most spacious and durable part of it, and best of all, to the basement.
8. If you have a car, try to drive as far as possible from the epicenter of the hurricane.
Children from kindergartens and schools must be sent home in advance. If a storm warning arrives too late, children should be placed in basements or central areas of buildings.
It is best to wait out a hurricane, tornado or storm in a shelter, a previously prepared shelter, or at least in a basement. However, often, a storm warning is given only a few minutes before the storm arrives, and during this time it is not always possible to get to shelter.
If you find yourself outside during a hurricane
2. You must not be on bridges, overpasses, overpasses, or in places where flammable and toxic substances are stored.
3. Hide under a bridge, reinforced concrete canopy, in a basement, cellar. You can lie down in a hole or any depression. Protect your eyes, mouth and nose from sand and soil.
4. You cannot climb onto the roof and hide in the attic.
5. If you are driving a car on the plain, stop, but do not leave the car. Close its doors and windows tightly. During snow storm Cover the engine from the radiator side with something. If the wind is not strong, you can shovel the snow from your car from time to time to avoid being buried under a thick layer of snow.
6. If you are in public transport, leave it immediately and seek shelter.
7. If the elements catch you in an elevated or open place, run (crawl) towards some kind of shelter (rocks, forest) that could dampen the force of the wind, but beware of falling branches and trees.
8. When the wind has died down, do not immediately leave the shelter, as the squall may recur in a few minutes.
9. Stay calm and don’t panic, help the victims.
How to behave after natural disasters
1. When leaving the shelter, look around to see if there are any overhanging objects, parts of structures, or broken wires.
2. Do not light gas or fire, do not turn on electricity until special services check the condition of communications.
3. Don't use the elevator.
4. Do not enter damaged buildings or go near downed electrical wires.
5. The adult population assists the rescuers.
Devices
The exact wind speed is determined using a device - an anemometer. If such a device does not exist, you can make a homemade wind measuring “Wild board” (Fig. 1), with sufficient measurement accuracy for wind speeds of up to ten meters per second.
Rice. 1. Homemade wind vane board Wilda:
1 - vertical tube (600 mm long) with a welded pointed upper end, 2 - front horizontal rod of the weather vane with a counterweight ball; 3 - weather vane impeller; 4 - upper frame; 5 - horizontal axis of the board hinge; 6 - wind measuring board (weighing 200 g). 7 - lower fixed vertical rod with cardinal indicators mounted on it: N - north, S - south, 3 - west, E - east; No. 1 - No. 8 - wind speed indicator pins.
The weather vane is installed at a height of 6 - 12 meters, above an open, flat surface. Under the weather vane there are arrows indicating the direction of the wind. Above the weather vane, to tube 1 on the horizontal axis 5, a wind measuring board 6 measuring 300x150 mm is hinged to frame 4. Board weight - 200 grams (adjusted using a reference device). Moving back from frame 4 is a segment of an arc attached to it (with a radius of 160 mm) with eight pins, of which four are long (140 mm each) and four are short (100 mm each). The angles at which they are fixed are with the vertical for pin No. 1-0°; No. 2 - 4°; No. 3 - 15.5°; No. 4 - 31°; No. 5 - 45.5°; No. 6 - 58°; No. 7 - 72°; No. 8-80.5°.
Wind speed is determined by measuring the angle of deflection of the board. Having determined the position of the wind measuring board between the pins of the arc, turn to the table. 1, where this position corresponds to a certain wind speed.
The position of the board between the pins gives only a rough idea of the wind speed, especially since the wind strength changes quickly and frequently. The board never remains in any one position for long, but constantly fluctuates within certain limits. Observing the changing slope of this board for 1 minute, determine its average slope (calculation by averaging maximum values) and only after that the average minute wind speed is judged. For high wind speeds exceeding 12-15 m/sec, the readings of this device have low accuracy (this limitation is the main drawback of the considered scheme).
Application
average speed winds on the Beaufort scale different years its application
table 2
| Point | Verbal characteristic |
Average wind speed (m/s) according to recommendations | ||||
| Simpson | Köppen | International Meteorological Committee | ||||
| 1906 | 1913 | 1939 | 1946 | 1963 | ||
| 0 | Calm | 0 | 0 | 0 | 0 | 0 |
| 1 | Quiet wind | 0,8 | 0,7 | 1,2 | 0,8 | 0,9 |
| 2 | Light breeze | 2,4 | 3,1 | 2,6 | 2,5 | 2,4 |
| 3 | Light wind | 4,3 | 4,8 | 4,3 | 4,4 | 4,4 |
| 4 | Moderate wind | 6,7 | 6,7 | 6,3 | 6,7 | 6,7 |
| 5 | Fresh breeze | 9,4 | 8,8 | 8,7 | 9,4 | 9,3 |
| 6 | Strong wind | 12,3 | 10,8 | 11,3 | 12,3 | 12,3 |
| 7 | strong wind | 15,5 | 12,7 | 13,9 | 15,5 | 15,5 |
| 8 | Very strong wind | 18,9 | 15,4 | 16,8 | 18,9 | 18,9 |
| 9 | Storm | 22,6 | 18,0 | 19,9 | 22,6 | 22,6 |
| 10 | Heavy storm | 26,4 | 21,0 | 23,4 | 26,4 | 26,4 |
| 11 | Fierce Storm | 30,0 | 27,1 | 30,6 | 30,5 | |
| 12 | Hurricane | 29,0 | 33,0 | 32,7 | ||
| 13 | 39,0 | |||||
| 14 | 44,0 | |||||
| 15 | 49,0 | |||||
| 16 | 54,0 | |||||
| 17 | 59,0 | |||||
The Hurricane Scale was developed by Herbert Saffir and Robert Simpson in the early 1920s to measure the potential damage of a hurricane. It is based on numerical values of maximum wind speed and includes an assessment of storm surges in each of five categories. In Asian countries, this natural phenomenon is called a typhoon (translated from Chinese as “great wind”), and in Northern and South America- called a hurricane. At quantification wind flow speed, the following abbreviations apply: km/h / mph- kilometers / miles per hour, m/s- meters per second.
table 3
| № | Category | Maximum speed wind | Storm waves, m | Effect on ground objects | Effect on the coastal zone |
| 1 | Minimum | 119-153 km/h 74-95 mph 33-42 m/s |
12-15 | Trees and bushes damaged | Minor damage to the piers, some small vessels in the anchorage were torn from their anchors |
| 2 | Moderate | 154-177 km/h 96-110mph 43-49 m/s |
18-23 | Significant damage to trees and bushes; some trees were downed, prefabricated houses were badly damaged | Significant damage to piers and marinas, with small vessels at anchor torn from their anchors |
| 3 | Significant | 178-209 km/h 111-129 mph 49-58 m/s |
27-36 | Large trees were downed, prefabricated houses were destroyed, and some small buildings had windows, doors and roofs damaged. | Heavy floods along coastline; small buildings on the shore were destroyed |
| 4 | Huge | 210-249 km/h 130-156 mph 58-69 m/s |
39-55 | Trees, bushes and billboards were toppled, prefabricated houses were destroyed to the ground, windows, doors and roofs were badly damaged | Areas located at an altitude of up to 3 meters above sea level are flooded; floods extend 10 km inland; damage from waves and debris carried by them |
| 5 | Catastrophe | >250 km/h >157 mph > 69 m/s |
More than 55 | All trees, bushes and billboards have been knocked down and many buildings have been seriously damaged; some buildings were completely destroyed; prefabricated houses demolished | Severe damage was caused to the lower floors of buildings up to 4.6 meters above sea level in an area extending 457 meters inland. Mass evacuations of the population from coastal areas are necessary |
Tornado scale
The tornado scale (Fujita-Pearson scale) was developed by Theodore Fujita to classify tornadoes by the degree of wind damage caused. Tornadoes are characteristic mainly of North America.
table 4
| Category | Speed, km/h | Damage |
| F0 | 64-116 | Destroys chimneys, damages tree crowns |
| F1 | 117-180 | Tears prefabricated (panel) houses from the foundation or overturns them |
| F2 | 181-253 | Significant destruction. Prefabricated houses are destroyed, trees are uprooted |
| F3 | 254-332 | Destroys roofs and walls, scatters cars, overturns trucks |
| F4 | 333-419 | Destroys fortified walls |
| F5 | 420-512 | Lifts houses and moves them a considerable distance |
Glossary of terms:
Leeward side object (protected from the wind by the object itself; an area of high pressure, due to strong deceleration of the flow) faces where the wind is blowing. In the picture - on the right. For example, on the water, small ships approach larger ships from their leeward side (where they are protected from waves and wind by the larger ship's hull). “Smoking” factories and enterprises should be located in relation to residential urban areas - on the leeward side (in the direction of the prevailing winds) and separated from these areas by sufficiently wide sanitary protection zones. 
Windward side object (hill, sea vessel) - on the side from which the wind blows. On the windward side of the ridges, upward movements of air masses occur, and on the leeward side, a downward airfall occurs. The greatest part of precipitation (in the form of rain and snow), caused by the barrier effect of the mountains, falls on their windward side, and on the leeward side the collapse of colder and drier air begins.
Approximate calculation of dynamic wind pressure per square meter billboard(perpendicular to the plane of the structure) installed near the roadway. In the example, the maximum storm wind speed expected in a given location is assumed to be 25 meters per second.
Calculations are carried out according to the formula:
P = 1/2 * (air density) * V^2 = 1/2 * 1.2 kg/m3 * 25^2 m/s = 375 N/m2 ~ 38 kilograms per square meter (kgf)
Notice that the pressure increases as the square of the speed. Take into account and include in the construction project sufficient margin of safety, stability (depending on the height of the support stand) and resistance to strong gusts of wind and precipitation, in the form of snow and rain.
At what wind speed are plane flights canceled? civil aviation
The reason for disruption of flight schedules, delays or cancellations of flights may be a storm warning from weather forecasters at the departure and destination airfields.
The meteorological minimum required for a safe (normal) take-off and landing of an aircraft is permissible limits changes in a set of parameters: wind speed and direction, line of sight, condition of the airfield runway and the height of the lower cloud limit. Bad weather, in the form of intense atmospheric precipitation(rain, fog, snow and blizzard), with extensive frontal thunderstorms - can also cause the cancellation of flights from the airport.
The values of meteorological minimums may vary for specific aircraft (by their types and models) and airports (by class and the availability of sufficient ground equipment, depending on the characteristics of the terrain surrounding the airfield and the high mountains present), and are also determined by the qualifications and flight experience of the crew pilots , the ship's commander. The worst minimum is taken into account and for execution.
A flight ban is possible in case of bad weather at the destination airfield, if there are not two alternate airports nearby with acceptable weather conditions.
In strong winds, planes take off and land against the air flow (taxiing, for this purpose, to the appropriate runway). In this case, not only safety is ensured, but also the takeoff run distance and landing run distance are significantly reduced. Limitations on the lateral and tailwind components of wind speed, for most modern civil aircraft, are approximately 17-18 and 5 m/s, respectively. The danger of a large roll, drift and turn of an airliner during its takeoff and landing is represented by an unexpected and strong gusty wind (squall).
http://www.meteorf.ru - Roshydromet (Federal Service for Hydrometeorology and Environmental Monitoring). Hydrometeorological Research Center of the Russian Federation.
Www.meteoinfo.ru - new website of the Hydrometeorological Center of the Russian Federation.
Wind(the horizontal component of air movement relative to the earth's surface) is characterized by direction and speed.
Wind speed measured in meters per second (m/s), kilometers per hour (km/h), knots or Beaufort points (wind force). Knot – maritime measure of speed, 1 nautical mile per hour, approximately 1 knot is equal to 0.5 m/s. The Beaufort scale (Francis Beaufort, 1774-1875) was created in 1805.
Direction of the wind(from where it blows) is indicated either in points (on a 16-point scale, for example, north wind - N, northeast - NE, etc.), or in angles (relative to the meridian, north - 360° or 0°, east - 90°, south – 180°, west – 270°), fig. 1.
| Name of the wind | Speed, m/s | Speed, km/h | Nodes | Wind force, points | Wind action | |
|---|---|---|---|---|---|---|
| Calm | 0 | 0 | 0 | 0 | The smoke rises vertically, the leaves of the trees are motionless. Mirror smooth sea | |
| Quiet | 1 | 4 | 1-2 | 1 | The smoke deviates from the vertical direction, there are slight ripples in the sea, there is no foam on the ridges. Wave height up to 0.1 m | |
| Easy | 2-3 | 7-10 | 3-6 | 2 | You can feel the wind on your face, the leaves rustle, the weather vane begins to move, there are short waves at sea with a maximum height of up to 0.3 m | |
| Weak | 4-5 | 14-18 | 7-10 | 3 | The leaves and thin branches of the trees are swaying, light flags are swaying, there is a slight disturbance on the water, and occasionally small “lambs” are formed. Average wave height 0.6 m | |
| Moderate | 6-7 | 22-25 | 11-14 | 4 | The wind raises dust and pieces of paper; Thin branches of trees sway, white “lambs” on the sea are visible in many places. Maximum wave height up to 1.5 m | |
| Fresh | 8-9 | 29-32 | 15-18 | 5 | Branches and thin tree trunks sway, you can feel the wind with your hand, and white “lambs” are visible on the water. Maximum wave height 2.5 m, average - 2 m | |
| Strong | 10-12 | 36-43 | 19-24 | 6 | Thick tree branches sway, thin trees bend, telephone wires hum, umbrellas are difficult to use; white foamy ridges occupy large areas, and water dust is formed. Maximum wave height - up to 4 m, average - 3 m | |
| Strong | 13-15 | 47-54 | 25-30 | 7 | Tree trunks sway, large branches bend, it is difficult to walk against the wind, wave crests are torn off by the wind. Maximum wave height up to 5.5 m | |
| Very strong | 16-18 | 58-61 | 31-36 | 8 | Thin and dry branches of trees break, it is impossible to speak in the wind, it is very difficult to walk against the wind. Strong seas. Maximum wave height up to 7.5 m, average - 5.5 m | |
| Storm | 19-21 | 68-76 | 37-42 | 9 | Large trees are bending, the wind is tearing tiles off the roofs, very rough seas, high waves (maximum height - 10 m, average - 7 m) | |
| Heavy storm | 22-25 | 79-90 | 43-49 | 10 | Rarely happens on land. Significant destruction of buildings, wind knocks down trees and uproots them, the surface of the sea is white with foam, strong crashing waves are like blows, very high waves (maximum height - 12.5 m, average - 9 m) | |
| Fierce Storm | 26-29 | 94-104 | 50-56 | 11 | It is observed very rarely. Accompanied by destruction over large areas. The sea has exceptionally high waves (maximum height - up to 16 m, average - 11.5 m), small vessels are sometimes hidden from view | |
| Hurricane | More than 29 | More than 104 | More than 56 | 12 | Serious destruction of capital buildings |
§ 35. Wave regime.
Waves observed on the surface of water are divided into three types.
Wind waves formed as a result of the action of wind.
Seismic waves arising in the oceans as a result of an earthquake and reaching heights of 10-30 near the coast m.
Seiches are waves that are formed in a limited basin adjacent to the sea as a result of an imbalance of the water surface caused by strong winds or soil vibrations.
For navigation on rivers and in coastal areas In the sea, only wind waves (friction waves) are significant.
Waves consist of alternating shafts and troughs (Fig. 79), where the wavelength l, measured in meters, is the horizontal distance between adjacent crests or troughs of the waves; wave height h - vertical distance from the base to the wave crest. Wave speed, measured in m/sec,- the distance that the crest or trough of a wave travels per unit time in the direction of its movement.
The period of a wave is the period of time during which two adjacent wave crests successively pass through the same point, measured in seconds. The slope angle or steepness of a wave is denoted by a. Wave front is a line perpendicular to the direction of wave movement. This direction, like the course, is determined in numbers or degrees. The ratio of the wave height h to its length l also characterizes the steepness of the waves. It is less on the seas and oceans and more on reservoirs and lakes.
Wind waves arise with the wind; when the wind stops, these waves in the form of a dead swell, gradually fading, continue to move in the same direction.
Wind waves depend on the size of the water space open for wave acceleration, wind speed and time of action in one direction, as well as depth. As the depth decreases, the wave becomes steeper. A weak wind blowing for a long time over a large expanse of water can cause more significant waves than a strong short-term wind on a small water surface. The height of the wave is related to the degree of waves and is determined by a special wave scale (see Table 3).
Wind waves are asymmetrical, their windward slope is gentle, their leeward slope is steep. Since the wind is on top part the waves act more strongly than on the lower one, the crest of the wave crumbles, forming “lambs”.
Swell is a disturbance that continues after the wind has already died down, weakened or changed direction. A disturbance that spreads by inertia in complete calm is called a dead swell.
Waves are regular when their crests are clearly visible, and irregular when the waves do not have clearly defined crests and are formed without any visible pattern. The crests of the waves are perpendicular to the direction of the wind in the open sea, lake, reservoir, but near the shore they take a position parallel to the coastline, running onto the shores.
A crowd is a chaotic accumulation of waves formed when direct waves meet reflected ones. The overturning of the crest of a moving wave on a steep bank forms reverse faults that have great destructive power.
The running of waves onto a sloping shore with an increase in height and steepness and subsequent overturning onto the shore is called a surf. Breakers form over banks or reefs, serving as a sign of underwater danger.
The waves calm down somewhat from heavy rain, from algae and oil floating on the surface of the water.
In normal storms the length is long sea wave happens from 60 to 150 m, height from 6 to 8 m with a period of 6-10 seconds. The steepness of the wave reaches 1/20 - 1/10. On reservoirs and deep lakes the wave steepness is 1/10 - 1/15. The wave height at the reservoir usually reaches 2.5-3.0 m, on lakes up to 3.5 m. On rivers and canals the wave height is usually less - 0.6 m, but sometimes, especially during spring waters, it can reach 1 m.
Table 3
Anxiety scale.
|
Wave height (from to, m) |
Excitement level in points |
Characteristic |
Signs for determining the state of the surface of a sea, lake, large reservoir |
|
There is no excitement |
Mirror-smooth surface |
||
|
Up to 0.25 |
Weak |
Ripple, small wave crests appear |
|
|
0,25-0,75 |
Moderate |
Small wave crests begin to capsize, but the foam is not white, but glassy |
|
|
0,75-1,25 |
Significant |
Small waves, the crests of some of them overturn, forming in places white swirling foam - “lambs” |
|
|
1,25-2,0 |
Same |
The waves take on a well-defined shape, “lambs” are formed everywhere |
|
|
2,0-3,5 |
Strong |
High crests appear, their foaming peaks occupy large areas, the wind begins to tear off the foam from the crests of the waves |
|
|
3,5-6,0 |
Same |
The crests outline long shafts of wind waves; foam, torn from the crests by the wind, begins to stretch out in strips along the slopes of the waves |
|
|
6,0-8,5 |
Very strong |
Long strips of wind-blown foam cover the slopes of the waves, merging in places and reaching their toes |
|
|
8,5-11,0 |
VIII |
Same |
The foam covers the slopes of the waves in wide, dense, merging stripes, causing the surface to become white, only in places in the troughs of the waves are areas free of foam visible |
|
11.0 or more |
Exceptional |
The surface of the sea is covered with a dense layer of foam, the air is filled with water dust and spray, visibility is significantly reduced |
Maximum wave heights in the oceans reach 20 m. On the seas, lakes and reservoirs* they are different, for example: in the Northern - 9, Mediterranean - 8, Okhotsk - 7, on Lakes Baikal and Ladoga - 6, Black - 6 and Caspian - 10, on the Bratsk Reservoir - 4, 5 (in places where the depth is 100 m), in the Rybinsk Reservoir 2.7, in the Tsimlyansk Reservoir - 4.5, Kuibyshevsky - 3, in the White Sea and the Gulf of Finland - 2.5 m; in the lower reaches of the Volga during a storm, waves reach a height of 1.2 m.
To get acquainted with wind waves in a certain area of the reservoir, use a special atlas of wave phenomena. For one reason or another, an amateur cannot always use an atlas. In Fig. Figure 80 shows a graph for determining the wave height depending on the wind speed and the length of its acceleration. The schedule is valid only for freshwater bodies of water: reservoirs, lakes and rivers. The graph does not take into account the bottom topography and the surface topography of the coast, so it gives a small percentage of error.
Before setting sail on a wide section of a reservoir or river, you need to determine the height of the wave on the route along which the ship must follow. Suppose, according to the weather report transmitted by radio before setting sail, it was reported that cloudy weather with no precipitation and a moderate northeast wind are expected.
Using a map of the reservoir, we determine the location, area, course, route and distance in kilometers from the northeastern shore from where the wind blows. We obtained a wave acceleration length of 20 km.
From the scale for visual assessment of wind strength (Table 3) we determine that moderate wind can have a speed from 5.3 to 7.4 m/sec. On the graph (Fig. 85) we take curve 7 m/sec, by which we find that with an acceleration length of 20 km the wave height will be 0.65 m.
As a result, in accordance with the navigational qualities of the vessel and other data, it is possible to decide whether it is necessary to change course or whether it is better not to set sail at all.
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