Beaufort scale - a conditional scale that allows you to visually assess the approximate strength of the wind by its effect on ground objects or by waves at sea. Developed by the English admiral and hydrographer Francis Beaufort (Eng. Francis Beaufort) in 1806.

Since 1874, it has been officially accepted for use in international synoptic practice. Since 1926, the Beaufort scale has additionally indicated wind strength in meters per second at a height of 10 meters from the surface. In the USA, in addition to the international 12-point scale, since 1955, a scale expanded to 17 points has been used, which is used for more accurate gradation of hurricane winds.

// Classification of wind strength, sea waves, and visibility at sea

Classification of wind strength, sea waves, and visibility at sea

Beaufort scale

0 points - calm
A mirror-smooth sea, almost motionless. Waves practically do not run up to the shore. The water is more like a quiet backwater of a lake than a sea coast. Haze may be observed above the surface of the water. The edge of the sea merges with the sky so that the border is not visible. Wind speed 0-0.2 km/h.

1 point - quiet
Light ripples on the sea. The height of the waves reaches up to 0.1 meters. The sea can still merge with the sky. There is a light, almost imperceptible breeze.

2 points - easy
Small waves, no more than 0.3 meters high. The wind speed is 1.6-3.3 m/s, you can feel it with your face. With such a wind, the weather vane begins to move.

3 points - weak
Wind speed 3.4-5.4 m/s. Slight roughness on the water, occasionally lambs appear. The average wave height is up to 0.6 meters. A weak surf is clearly visible. The weather vane spins without frequent stops, the leaves on the trees, flags and so on sway.

4 points - moderate
Wind - 5.5 - 7.9 m / s - raises dust and small pieces of paper. The weather vane spins continuously, the thin branches of the trees bend. The sea is restless, in many places lambs are visible. Wave height up to 1.5 meters.

5 points - fresh
Almost the entire sea is covered with white lambs. Wind speed 8 - 10.7 m/s, wave height 2 meters. Branches and thin tree trunks sway.

6 points - strong
The sea is covered with white ridges in many places. The height of the waves reaches 4 meters, the average height is 3 meters. Wind speed 10.8 - 13.8 m/s. Thin tree trunks bend, and thick branches of trees, telephone wires buzz.

7 points - strong
The sea is covered with white foamy ridges, which are blown off the surface of the water from time to time by the wind. The wave height reaches 5.5 meters, the average height is 4.7 meters. Wind speed 13.9 - 17.1 m/s. Medium tree trunks sway, branches bend.

8 points - very strong
Strong waves, foam on each crest. The height of the waves reaches 7.5 meters, the average height is 5.5 meters. Wind speed 17.2 - 20 m/s. It is difficult to go against the wind, it is almost impossible to talk. Thin branches of trees break.

9 points - storm
High waves on the sea, reaching 10 meters; average height 7 meters. Wind speed 20.8 - 24.4 m/s. Large trees bend, medium branches break. The wind rips off poorly reinforced roof coverings.

10 points - strong storm
The sea is white. Waves crash on the shore or on the rocks with a crash. The maximum wave height is 12 meters, the average height is 9 meters. The wind, at a speed of 24.5 - 28.4 m/s, rips off roofs, significant damage to buildings.

11 points - fierce storm
High waves reach 16 meters, with an average height of 11.5 meters. Wind speed 28.5 - 32.6 m/s. Accompanied by great destruction on land.

12 points - hurricane
Wind speed 32.6 m/s. Serious damage to capital buildings. The wave height is over 16 meters.

Sea wave scale

In contrast to the generally accepted twelve-point system for estimating wind, there are several estimates of sea waves. British, American and Russian grading systems are generally accepted. All scales are based on a parameter that determines the average height of significant waves (according to the site savelyev.info). This setting is called Significance Wave Height (SWH). In the American scale, 30% of significant waves are taken, in the British 10%, in the Russian 3%. Wave height is measured from the crest (the top of the wave) to the trough (the base of the trough).
Below is a description of the height of the waves.

0 points - calm
1 point - ripples (SWH< 0,1 м)
2 points - weak waves (SWH 0.1 - 0.5 m)
3 points - light waves (SWH 0.5 - 1.25 m)
4 points - moderate waves (SWH 1.25 - 2.5 m)
5 points - rough sea (SWH 2.5 - 4.0 m)
6 points - very rough sea (SWH 4.0 - 6.0 m)
7 points - strong sea (SWH 6.0 - 9.0 m)
8 points - very strong sea (SWH 9.0 - 14.0 m)
9 points - phenomenal sea (SWH > 14.0 m)
In this scale, the word "storm" is not applicable. Since it is not determined by the strength of the storm, but by the height of the wave. Storm is defined by Beaufort.
For the WH parameter for all scales, it is precisely a part of the waves (30%, 10%, 3%) that is taken because the magnitude of the waves is not the same. At a certain time interval there are waves, for example, 9 meters, as well as 5, 4, etc. Therefore, each scale has its own SWH value, where a certain percentage of the highest waves is taken. There are no instruments for measuring wave height. Therefore, there is no exact definition of the score. The definition is conditional.
On the seas, as a rule, the wave height reaches 5-6 meters in height, and up to 80 meters in length.

Visibility scale

Visibility is the maximum distance at which objects are detected during the day and navigation lights at night. Visibility depends on weather conditions. In metrology, the influence of weather conditions on visibility is determined by a conditional scale of points. This scale is a way of indicating the transparency of the atmosphere. Distinguish between day and night visibility. Below is a daily scale for determining the range of visibility.
Up to 1/4 cable
About 46 meters. Very poor visibility. Thick fog or blizzard.
Up to 1 cable
About 185 meters. Bad visibility. Thick fog or sleet.
2-3 cables
370 - 550 meters. Bad visibility. Fog, wet snow.
1/2 mile
About 1 km. Haze, thick haze, snow.
1/2 - 1 mile
1 - 1.85 km. Average visibility. Snow, heavy rain
1 - 2 miles
1.85 - 3.7 km. Haze, mist, rain.
2 - 5 miles
3.7 - 9.5 km. Light haze, haze, light rain.
5 - 11 miles
9.3 - 20 km. Good visibility. Visible horizon.
11 - 27 miles
20 - 50 km. Very good visibility. The horizon is clearly visible.
27 miles
Over 50 km. Exceptional visibility. The horizon is clearly visible, the air is transparent.

Wind is a horizontal flow of air that has a number of specific characteristics: strength, direction and speed. It was to determine the speed of the winds that the Irish admiral at the beginning of the 19th century developed a special table. The so-called Beaufort scale is still used today. What is a scale? How to use it correctly? And what does the Beaufort scale not allow you to determine?

What is wind?

The scientific definition of this concept is as follows: wind is an air flow that moves parallel to the earth's surface from an area of ​​high to an area of ​​low atmospheric pressure. This phenomenon is typical not only for our planet. Thus, the strongest winds in the solar system blow on Neptune and Saturn. And the terrestrial winds, in comparison with them, may seem like a light and very pleasant breeze.

The wind has always played an important role in human life. He inspired ancient writers to create mythical stories, legends and fairy tales. It is thanks to the wind that a person has the opportunity to overcome significant distances by sea (with the help of sailboats) and by air (by means of balloons). The wind is also involved in the "building" of many earthly landscapes. So, it transfers millions of grains of sand from place to place, thereby forming unique eolian landforms: dunes, dunes and sandy ridges.

At the same time, winds can not only create, but also destroy. Their gradient fluctuations can provoke a loss of control over the aircraft. A strong wind significantly expands the scale of forest fires, and on large reservoirs it gives rise to huge waves that destroy houses and claim the lives of people. That is why it is so important to study and measure the wind.

Basic wind parameters

It is customary to distinguish four main wind parameters: strength, speed, direction and duration. All of them are measured using special devices. The strength and speed of the wind is determined using the so-called anemometer, the direction - with the help of a weather vane.

Based on the duration parameter, meteorologists distinguish squalls, breezes, storms, hurricanes, typhoons and other types of winds. The direction of the wind is determined by the side of the horizon from which it blows. For convenience, they are abbreviated with the following Latin letters:

• N (northern).
• S (southern).
• W (western).
• E (eastern).
• C (calm).

Finally, wind speed is measured at a height of 10 meters using anemometers or special radars. Moreover, the duration of such measurements in different countries of the world is not the same. For example, at American meteorological stations, the average speed of air currents is taken into account for 1 minute, in India - for 3 minutes, and in many European countries - for 10 minutes. The classic instrument for presenting data on wind speed and strength is the so-called Beaufort scale. How and when did she appear?

Who is Francis Beaufort?

Francis Beaufort (1774-1857) - Irish sailor, military admiral and cartographer. He was born in the small town of An-Waw in Ireland. After graduating from school, the 12-year-old boy continued his studies under the guidance of the famous professor Usher. During this period, he first showed an extraordinary ability to study the "marine sciences". As a teenager, he joined the East India Company and took an active part in filming the Java Sea.

It should be noted that Francis Beaufort grew up as a rather bold and courageous guy. So, during the wreck of the ship in 1789, the young man showed great dedication. Having lost all his food and personal belongings, he managed to save the team's valuable tools. In 1794, Beaufort took part in a naval battle against the French and heroically towed a ship hit by enemy fire.

Development of the wind scale

Francis Beaufort was extremely industrious. Every day he woke up at five o'clock in the morning and immediately set to work. Beaufort was a significant authority among the military and sailors. However, he gained worldwide fame thanks to his unique development. While still a midshipman, the inquisitive young man kept a daily diary of observations of the weather. Later, all these observations helped him to draw up a special scale of winds. In 1838, she was officially approved by the British Admiralty.

In honor of the famous scientist and cartographer, one of the seas, an island in Antarctica, a river and a cape in northern Canada are named. And Francis Beaufort became famous for creating a polyalphabetic military cipher, also named after him.

Beaufort scale and its features

The scale represents the earliest classification of winds according to their strength and speed. It was developed on the basis of meteorological observations in the open sea. Initially, the classic Beaufort wind scale is a twelve-point scale. It was only in the middle of the 20th century that it was expanded to 17 levels in order to distinguish between hurricane-force winds.

Wind strength on the Beaufort scale is determined by two criteria:

1. According to its impact on various ground objects and objects.
2. According to the degree of excitement of the open sea.

It is important to note that the Beaufort scale does not allow determining the duration and direction of air flows. It contains a detailed classification of winds according to their strength and speed.

Beaufort scale: table for sushi

Below is a table with a detailed description of the impact of wind on ground objects and objects. The scale, developed by the Irish scientist F. Beaufort, consists of twelve levels (points).

Beaufort table of sea conditions

In oceanography, there is such a thing as the state of the sea. It includes the height, frequency and strength of sea waves. Below is the Beaufort scale (table), which will help determine the strength and speed of the wind, based on these signs.

Thus, thanks to the Beaufort scale, people can observe the wind and evaluate its strength. This makes it possible to make the most accurate weather forecasts.

Wind- this is a horizontal movement (air flow parallel to the earth's surface), resulting from uneven distribution of heat and atmospheric pressure and directed from a high pressure zone to a low pressure zone

The 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. The strength of the wind is measured in points.

Wind in boots, m/s, km/h

Beaufort scale- conditional scale for visual assessment and recording of wind strength (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 accepted for widespread (on land and sea) use in international synoptic practice. In subsequent years, it was changed and refined (Table 2). The 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 strength of the wind in the scale is determined by the interaction of the wind with various objects. In recent years, the strength of the wind is more often estimated by the speed, measured in meters per second - at the earth's surface, at a height of about 10 m above an open, flat surface.

The table shows the Beaufort scale, adopted in 1963 by the World Meteorological Organization. The sea wave scale is nine-point (the parameters are given for a large sea area; in small water areas, the wave is less). Descriptions of the action from 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 temperature. On the planet Mars, for example, the ratios will be different.

Wind strength in points on the Beaufort scale and sea waves

Table 1

To make it easier to remember(compiled by: site author site)

3 - Weak - 5 m / s (~ 20 km / h) - leaves and thin branches of trees sway continuously
5 - Fresh - 10 m / s (~ 35 km / h) - pulls out big flags, whistles in the ears
7 - Strong - 15 m / s (~ 55 km / h) - telegraph wires are buzzing, it is difficult to go against the wind
9 - Storm - 25 m / s (90 km / h) - wind knocks down trees, destroys buildings

* The length of the wind wave on the surface of water bodies (rivers, seas, etc.) is the smallest distance, horizontally, between the tops of neighboring ridges.

Dictionary:

Breeze– a weak coastal wind with a strength of up to 4 points.

normal wind- acceptable, optimal for something. For example, for sports windsurfing, sufficient wind thrust is needed (at least 6-7 meters per second), and when parachuting, on the contrary, calm weather is better (excluding lateral drift, strong gusts near the earth's surface and dragging the dome after landing).

storm is called a long and stormy wind up to a hurricane, with a force of more than 9 points (gradation on the Beaufort scale), accompanied by destruction on land and strong waves at sea (storm). Storms are: 1) squall; 2) dusty (sandy); 3) dust free; 4) snow. Squall storms start suddenly and end just as quickly. Their actions are characterized by enormous destructive power (such a 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 strength occur on the plains of the European part and in the steppe part of Siberia. Typically, storms are caused by the passage of an active atmospheric front, a deep cyclone, or a tornado.

Squall- a strong and sharp gust of wind (Peak gusts) with a speed of 12 m/s and above, usually accompanied by a thunderstorm. At a speed of more than 18-20 meters per second, a heavy wind blows away poorly fixed structures, signs and can break billboards and tree branches, cause power lines to break, which creates a danger to people and cars under them. A gusty, squally wind occurs during the passage of an atmospheric front and with a rapid change in pressure in a baric system.

Vortex- atmospheric formation with rotational movement of air around a vertical or inclined axis.

Hurricane(typhoon) - a wind of destructive force and considerable duration, the speed of which exceeds 120 km/h. "Lives", i.e. moves, a hurricane usually lasts 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 force can be compared to an earthquake. Homeland hurricanes - ocean expanses, closer to the equator. Cyclones saturated with water vapor from here leave to the west, more and more twisting and increasing speed. The diameters of these giant whirlwinds 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 are vertical vortices; squalls are more often horizontal, included in the structure of cyclones.

The word "tornado" is Russian, and comes from the semantic concept of "twilight", that is, a gloomy, thunderous situation. The tornado is a giant rotating funnel, inside which there is low pressure, and any objects that are in the way of the tornado 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. Deaths are short-lived. Some of them "live" 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, cripple a bridge, 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 the inhabitants of the city of Shaturia were warned in advance about the approach of a tornado, 1,300 people became its victims.

In Russia, tornadoes are more frequent in the summer months in the Urals, the Black Sea coast, the Volga region and Siberia.

Forecasters classify hurricanes, storms and tornadoes as emergency events with a moderate propagation speed, so most often it is possible to announce a storm warning in time. It can be transmitted through civil defense channels: after the sound of sirens " Attention everyone!"must listen to the message of the local television and radio.

Symbols on meteorological maps of weather phenomena associated with wind

In meteorology and hydrometeorology, the direction of the wind ("where it blows from") is indicated on the map in the form of an arrow, the type of plumage of which shows the average speed of the air flow. In air navigation - the name of the direction is different to the opposite. In navigation on water, the unit of speed (knot) of a vessel is taken to be one nautical mile per hour (ten knots correspond to approximately five meters per second).

On the weather map, a long feather of the wind arrow means 5 m/s, a short one - 2.5 m/s, in the form of a triangular flag - 25 m/s (follows after a combination of four long lines and 1 short one). In the example shown in the figure, there is a wind with a force of 7-8 m/s. With an unstable wind direction, a cross is placed at the end of the arrow.

The picture shows the symbols for the direction and speed of the wind used on weather maps, as well as an example of drawing icons and fragments from a hundred-cell matrix of weather symbols (for example, a snowstorm and a blowing snow, when there is a rise and redistribution of previously fallen snow in the surface air layer).

These symbols can be seen on the synoptic map of the Hydrometeorological Center of Russia (http://meteoinfo.ru) compiled as a result of the analysis of current data on the territory of Europe and Asia, which schematically shows the boundaries of the zones of warm and cold atmospheric fronts and the direction 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. Glue strips of plaster crosswise on the glass (so that fragments do not fly apart).

2. Prepare a supply of water and food, medicines, a flashlight, candles, a kerosene lamp, a battery 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. From light buildings, move to more durable 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 the storm warning comes too late, the children should be placed in basements or the center of buildings.

It is best to wait out a hurricane, a tornado or a storm in a shelter, a pre-prepared shelter, or at least in a basement. However, often, a storm warning is given just a few minutes before the arrival of the elements, and during this time it is not always possible to get to the shelter.

If you were outside during a hurricane

2. You can not be on bridges, overpasses, overpasses, in places where flammable and toxic substances are stored.

3. Hide under the bridge, reinforced concrete canopy, in the basement, cellar. You can lie down in a hole or any depression. Protect eyes, mouth and nose from sand and earth.

4. You can not climb onto the roof and hide in the attic.

5. If you are driving in a flat area, stop but do not leave the vehicle. Close its doors and windows more tightly. Cover the radiator side of the engine during a snow storm. If the wind is not strong, you can shovel the snow from the car from time to time so as not to be buried under a thick layer of snow.

6. If you are in public transport, leave it immediately and seek shelter.

7. If the elements caught you on an elevated or open place, run (crawl) towards some kind of shelter (to the rocks, forest) that could extinguish 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 a squall may repeat in a few minutes.

9. Stay calm and don't panic, help the injured.

How to behave after natural disasters

1. Leaving the shelter, look around for overhanging objects and parts of structures, broken wires.

2. Do not light gas and fire, do not turn on electricity until special services check the state of communications.

3. Do not use the elevator.

4. Do not enter damaged buildings, do not approach broken electrical wires.

5. The adult population provides assistance to rescuers.

Devices

The exact wind speed is determined using an instrument - an anemometer. If there is no such device, you can make a home-made wind-measuring "Wild board" (Fig. 1), with sufficient measurement accuracy for wind speeds up to ten meters per second.

Rice. 1. Homemade Wind Measuring Board-Wild Vane:
1 - a vertical tube (600 mm long) with a welded pointed upper end, 2 - a front horizontal weather vane rod with a counterweight ball-weight; 3 - weather vane impeller; 4 - upper frame; 5 - horizontal axis of the board hinge; 6 - wind board (weighing 200 g). 7 - lower fixed vertical rod with indicators of the cardinal points fixed on it: C - north, south - south, 3 - west, B - 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, arrows indicating the direction of the wind are fixedly fixed. Above the weather vane to the tube 1 on the horizontal axis 5 is hinged to the frame 4 wind board 6 measuring 300x150 mm. Board weight - 200 grams (adjusted according to the reference device). Extending back from frame 4 is an arc segment 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 the pin No. 1-0 °; №2 - 4°; No. 3 - 15.5°; #4 - 31°; No. 5 - 45.5 °; #6 - 58°; #7 - 72°; No. 8-80.5°.
The wind speed is determined by measuring the angle of deflection of the board. Having determined the position of the wind board between the arc pins, refer to Table. 1, where this position corresponds to a certain wind speed.
The position of the board between the pins gives only an approximate indication of the wind speed, especially since the wind strength changes quickly and often. The board never remains long in any one position, but constantly fluctuates within certain limits. Observing the changing inclination of this board for 1 minute, its average inclination is determined (calculation by averaging the maximum values) and only after that the average minute wind speed is judged. For a high wind speed exceeding 12-15 m/s, the readings of this device have low accuracy (in this limitation, this is the main drawback of the considered scheme).

Application

Average wind speed on the Beaufort scale in different years of its application

table 2

The Hurricane Scale was developed by Herbert Saffir and Robert Simpson in the early 1920s to measure the potential damage from a hurricane. It is based on numerical maximum wind speeds and includes an estimate of storm waves in each of the five categories. In Asian countries, this natural phenomenon is called a typhoon (translated from Chinese as “great wind”), and in North and South America it is called a hurricane. When quantifying wind flow speed, the following abbreviations apply: km/h / mph- kilometers / miles per hour, m/s- meters per second.

table 3

tornado scale

The tornado scale (Fujita-Pearson scale) was developed by Theodore Fujita to classify tornadoes according to the degree of damage caused by the wind. Tornadoes are typical mainly for North America.

table 4

Glossary of terms:

Leeward side of the object (protected from the wind by the object itself; an area of ​​increased pressure, due to strong flow deceleration) faces where the wind blows. In the picture - on the right. For example, on the water, small ships approach larger ships from their leeward side (there they are protected by the hull of a large ship from waves and wind). "Smoking" factories-enterprises should be located, in relation to residential urban buildings - on the leeward side (in the direction of the prevailing winds) and separated from these areas by fairly wide sanitary protection zones.


windward side object (hill, sea vessel) - on the side where the wind blows. On the windward side of the ridges, ascending movements of air masses occur, and on the leeward side, a downward airfall occurs. Most of the precipitation (in the form of rain and snow), due to the barrier effect of the mountains, falls on their windward side, and on the leeward side, a collapse of colder and drier air begins.

Approximate calculation of dynamic wind pressure per square meter of a billboard (perpendicular to the plane of the structure) installed near the road of the carriageway. In the example, the maximum storm wind speed expected at 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)

Note that the pressure increases with the square of the speed. Take into account and include in the construction project sufficient margin of safety, stability (also depends on the height of the support post) and resistance to strong gusts of wind and precipitation, in the form of snow and rain.

At what wind strength cancel flights of civil aviation aircraft

The reason for violation of the flight schedule, delay or cancellation of flights - may be a storm warning from weather forecasters, at the airports of departure and destination.

The meteorological minimum required for a safe (regular) takeoff and landing of an aircraft is the allowable limits for changes in a set of parameters: wind speed and direction, line of sight, the state of the airfield runway, and the height of the cloud base. Bad weather, in the form of intense precipitation (rain, fog, snow and blizzard), with extensive frontal thunderstorms, can also cause cancellation of flights from the air harbor.

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 features of the terrain surrounding the airfield and the existing high mountains), as well as due to the qualifications and flight experience of the crew pilots , commander of the ship. The worst minimum is taken into account and for execution.

Departure ban - possible in case of bad weather at the destination airport, if there are not, nearby, two alternative air harbors with acceptable weather conditions.

In strong winds, aircraft take off and land against the air flow (by taxiing, for this, to the appropriate lane). In this case, not only safety is ensured, but also the takeoff run and landing run are significantly reduced. Limitations on the lateral and tailwind components of the wind speed, for most modern civil aircraft, are approximately: 17-18 and 5 m/s, respectively. The danger of a large roll, demolition and reversal of an airliner, during its takeoff and landing, is represented by an unexpected and strong gusty wind (squall).

https://www.meteorf.ru - Roshydromet (Federal Service for Hydrometeorology and Environmental Monitoring). Hydrometeorological Research Center of the Russian Federation.

Www.meteoinfo.ru - new site of the Hydrometeorological Center of the Russian Federation.

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1 kilometer per hour [km/h] = 0.277777777777778 meter per second [m/s]

Initial value

Converted value

meter per second meter per hour meter per minute kilometer per hour kilometer per minute kilometers per second centimeter per hour centimeter per minute centimeter per second millimeter per hour millimeter per minute millimeter per second foot per hour foot per minute foot per second yard per hour yard per minute yard per second mile per hour mile per minute mile per second knot knot (Brit.) speed of light in vacuum first space velocity second space velocity third space velocity earth's rotation speed sound speed in fresh water sound speed in sea water (20°C, depth 10 meters) Mach number (20°C, 1 atm) Mach number (SI standard)

Bulk charge density

More about speed

General information

Speed ​​is a measure of the distance traveled in a given time. Velocity can be a scalar quantity or a vector value - the direction of motion is taken into account. The speed of movement in a straight line is called linear, and in a circle - angular.

Speed ​​measurement

average speed v find by dividing the total distance traveled ∆ x for the total time ∆ t: v = ∆x/∆t.

In the SI system, speed is measured in meters per second. Also commonly used are kilometers per hour in the metric system and miles per hour in the US and UK. When, in addition to the magnitude, the direction is also indicated, for example, 10 meters per second to the north, then we are talking about vector speed.

The speed of bodies moving with acceleration can be found using the formulas:

• a, with initial speed u during the period ∆ t, has a final speed v = u + a×∆ t.
• A body moving with constant acceleration a, with initial speed u and final speed v, has an average speed ∆ v = (u + v)/2.

Average speeds

The speed of light and sound

According to the theory of relativity, the speed of light in a vacuum is the highest speed at which energy and information can travel. It is denoted by the constant c and equal to c= 299,792,458 meters per second. Matter cannot move at the speed of light because it would require an infinite amount of energy, which is impossible.

The speed of sound is usually measured in an elastic medium and is 343.2 meters per second in dry air at 20°C. The speed of sound is lowest in gases and highest in solids. It depends on the density, elasticity, and shear modulus of the substance (which indicates the degree of deformation of the substance under shear loading). Mach number M is the ratio of the speed of a body in a liquid or gas medium to the speed of sound in this medium. It can be calculated using the formula:

M = v/a,

Where a is the speed of sound in the medium, and v is the speed of the body. The Mach number is commonly used in determining speeds close to the speed of sound, such as aircraft speeds. This value is not constant; it depends on the state of the medium, which, in turn, depends on pressure and temperature. Supersonic speed - speed exceeding 1 Mach.

Vehicle speed

Below are some vehicle speeds.

• Passenger aircraft with turbofan engines: the cruising speed of passenger aircraft is from 244 to 257 meters per second, which corresponds to 878–926 kilometers per hour or M = 0.83–0.87.
• High-speed trains (like the Shinkansen in Japan): These trains reach top speeds of 36 to 122 meters per second, i.e. 130 to 440 kilometers per hour.

animal speed

The maximum speeds of some animals are approximately equal:

human speed

• Humans walk at about 1.4 meters per second, or 5 kilometers per hour, and run at up to about 8.3 meters per second, or 30 kilometers per hour.

Examples of different speeds

four dimensional speed

In classical mechanics, the vector velocity is measured in three-dimensional space. According to the special theory of relativity, space is four-dimensional, and the fourth dimension, space-time, is also taken into account in the measurement of speed. This speed is called four-dimensional speed. Its direction may change, but the magnitude is constant and equal to c, which is the speed of light. Four-dimensional speed is defined as

U = ∂x/∂τ,

Where x represents the world line - a curve in space-time along which the body moves, and τ - "proper time", equal to the interval along the world line.

group speed

Group velocity is the velocity of wave propagation, which describes the propagation velocity of a group of waves and determines the rate of wave energy transfer. It can be calculated as ∂ ω /∂k, Where k is the wave number, and ω - angular frequency. K measured in radians / meter, and the scalar frequency of wave oscillations ω - in radians per second.

Hypersonic speed

Hypersonic speed is a speed exceeding 3000 meters per second, that is, many times higher than the speed of sound. Solid bodies moving at such a speed acquire the properties of liquids, since due to inertia, the loads in this state are stronger than the forces that hold the molecules of matter together during a collision with other bodies. At ultra-high hypersonic speeds, two colliding solid bodies turn into gas. In space, bodies move exactly at this speed, and engineers designing spacecraft, orbital stations, and spacesuits must take into account the possibility of a station or astronaut colliding with space debris and other objects when working in outer space. In such a collision, the skin of the spacecraft and the suit suffer. Equipment designers conduct hypersonic collision experiments in special laboratories to determine how strong impact suits can withstand, as well as skins and other parts of the spacecraft, such as fuel tanks and solar panels, by testing them for strength. To do this, spacesuits and skin are subjected to impacts by various objects from a special installation with supersonic speeds exceeding 7500 meters per second.