15m with strong wind. How is the decision to fly made? Examples of different speeds

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.

Wind is the movement of air in a horizontal direction along the earth's surface. In which direction it blows depends on the distribution of pressure zones in the planet's atmosphere. The article deals with issues related to the speed and direction of the wind.

Perhaps, absolutely calm weather will be a rare phenomenon in nature, since you can constantly feel that a light breeze is blowing. Since ancient times, mankind has been interested in the direction of air movement, so the so-called weather vane or anemone was invented. The device is an arrow freely rotating on a vertical axis under the influence of wind force. She points his direction. If you determine the point on the horizon from which the wind blows, then the line drawn between this point and the observer will show the direction of air movement.

In order for an observer to convey information about the wind to other people, concepts such as north, south, east, west and their various combinations are used. Since the totality of all directions forms a circle, the verbal formulation is also duplicated by the corresponding value in degrees. For example, North wind means 0 o (the blue compass needle points due north).

The concept of the wind rose

Speaking about the direction and speed of movement of air masses, a few words should be said about the wind rose. It is a circle with lines showing how air flows. The first mention of this symbol was found in the books of the Latin philosopher Pliny the Elder.

The entire circle, reflecting the possible horizontal directions of the forward movement of air, is divided into 32 parts on the wind rose. The main ones are north (0 o or 360 o), south (180 o), east (90 o) and west (270 o). The resulting four parts of the circle are divided further, forming the northwest (315 o), northeast (45 o), southwest (225 o) and southeast (135 o). The resulting 8 parts of the circle are again divided in half each, which forms additional lines on the wind rose. Since the result is 32 lines, the angular distance between them is equal to 11.25 o (360 o /32).

Note that distinctive feature The wind rose is an image of a fleur-de-lis located above the north icon (N).

Where does the wind blow from?

Horizontal movements of large air masses are always carried out from areas of high pressure to areas of lower air density. At the same time, you can answer the question of what wind speed is by studying the location on geographical map isobars, that is, broad lines within which air pressure is constant. The speed and direction of movement of air masses is determined by two main factors:

• The wind always blows from the areas where the anticyclone stands to the areas covered by the cyclone. This can be understood if we remember that in the first case we are talking about zones of high pressure, and in the second case - low pressure.
• Wind speed is in direct proportion to the distance that separates two adjacent isobars. Indeed, the greater this distance, the weaker the pressure drop will be felt (in mathematics they say a gradient), which means that the forward movement of air will be slower than in the case of small distances between isobars and large pressure gradients.

Factors affecting wind speed

One of them, and the most important one, has already been voiced above - this is the pressure gradient between neighboring air masses.

In addition, the average wind speed depends on the topography of the surface over which it blows. Any irregularities in this surface significantly hinder the forward movement of air masses. For example, everyone who has been in the mountains at least once should have noticed that the winds are weak at the foot. The higher you climb the mountainside, the stronger the wind is felt.

For the same reason, winds blow stronger over the sea than over land. It is often eroded by ravines, covered with forests, hills and mountain ranges. All these heterogeneities, which are not over the seas and oceans, slow down any gusts of wind.

High above the earth's surface (on the order of several kilometers) there are no obstacles to the horizontal movement of air, so the wind speed in the upper troposphere is high.

Another factor that is important to consider when talking about the speed of movement of air masses is the Coriolis force. It is generated due to the rotation of our planet, and since the atmosphere has inertial properties, any movement of air in it is deflected. Due to the fact that the Earth rotates from west to east around its own axis, the action of the Coriolis force leads to the deviation of the wind to the right in the northern hemisphere, and to the left in the southern.

Curiously, this effect of the Coriolis force, which is negligible at low latitudes (tropics), has a strong influence on the climate of these zones. The fact is that the slowdown in wind speed in the tropics and at the equator is compensated by increased updrafts. The latter, in turn, lead to the intense formation of cumulus clouds, which are sources of strong tropical showers.

Instrument for measuring wind speed

It is an anemometer, which consists of three cups located at an angle of 120 o relative to each other, and fixed on a vertical axis. The principle of operation of an anemometer is quite simple. When the wind blows, the cups experience its pressure and begin to rotate on the axis. The stronger the air pressure, the faster they spin. By measuring the speed of this rotation, one can accurately determine the wind speed in m/s (meters per second). Modern anemometers are equipped with special electrical systems that independently calculate the measured value.

The instrument of wind speed based on the rotation of the cups is not the only one. There is another simple tool called the pitot tube. This device measures the dynamic and static wind pressure, the difference between which can accurately calculate its speed.

Beaufort scale

Information about wind speed, expressed in meters per second or kilometers per hour, for most people - and especially for sailors - says little. Therefore, in the 19th century, the English admiral Francis Beaufort proposed to use some empirical scale for evaluation, which consists of a 12-point system.

The higher the Beaufort scale, the stronger the wind blows. For example:

• The number 0 corresponds to absolute calm. With it, the wind blows at a speed not exceeding 1 mph, that is, less than 2 km / h (less than 1 m / s).
• The middle of the scale (number 6) corresponds to a strong breeze, the speed of which reaches 40-50 km/h (11-14 m/s). Such a wind can lift big waves on the sea.
• The maximum on the Beaufort scale (12) is a hurricane whose speed exceeds 120 km/h (more than 30 m/s).

Major winds on planet Earth

They are usually classified into one of four types in the atmosphere of our planet:

• Global. They are formed as a result of the different ability of continents and oceans to heat up from the sun's rays.
• Seasonal. These winds change with the season of the year, which determines how much solar energy a certain area of ​​the planet receives.
• Local. They are associated with features geographical location and topography of the area in question.
• Rotating. These are the strongest movements of air masses that lead to the formation of hurricanes.

Why is it important to study the winds?

In addition to the fact that information about wind speed is included in the weather forecast, which every inhabitant of the planet takes into account in his life, air movement plays an important role in a number of natural processes.

So, he is a carrier of plant pollen and is involved in the distribution of their seeds. In addition, wind is one of the main sources of erosion. Its destructive effect is most pronounced in deserts, when the terrain changes dramatically during the day.

It should also not be forgotten that the wind is the energy that people use in economic activity. According to general estimates, wind energy makes up about 2% of all solar energy falling on our planet.

Interestingly, the concept of non-flying weather» for passengers and pilots can sometimes be very different. What is “heavy fog” for a passenger may turn out to be “a veil over which a bright sun shines” for a pilot. And in the same way, what is “normal weather” for the passenger, for the pilot “the inability to land the plane at the destination due to strong crosswinds and icing on the runway.”

"Non-flying weather" is not just a natural phenomenon like a downpour, heavy snowfall or fog.

This term refers to several factors, such as:

Technical parameters of the aircraft,

Technical equipment and condition of a particular airport,

pilot training,

direct weather conditions.

The technical parameters of an aircraft are the data set by the manufacturer, under which the safe operation of the aircraft is possible. That is, for example, if the airport is well equipped and can handle flights in heavy fog, and a particular aircraft is not equipped with sufficiently modern navigation devices for landing in very low visibility conditions, then the flight cannot be operated. Since a 100% successful landing cannot be guaranteed, and this poses a threat to passengers and crew. Roughly speaking, the aircraft on instruments may "not see" the runway.

Maldives Airport is a single runway on an island in the open ocean.

Runway at Hulule Airport, Maldives

There are airfields equipped with the latest technical innovations, and they can receive flights in conditions of almost zero visibility. And there are airports where the minimum visibility should be, for example, 600 or 800m. And even if the aircraft is equipped with the latest technology, in conditions of poor visibility, the flight to this airport cannot be performed.

When performing any flight, of course, the professional training of pilots is taken into account. It is not enough that the aircraft be "the latest model with all the technical innovations." It would be nice if the pilots knew how to use these same innovations and had supporting documents. Then, "and we will fly away into the fog, and we will sit down in the rain."

Well, the most interesting - weather.

By weather conditions, we passengers, as a rule, mean heavy rain or snowfall, strong wind, hail, lightning, fog.

For pilots, three factors are decisive:

- state runway ,

- visibility,

- wind.

Runway condition- this is both the state of the strip itself and the consequences weather conditions on this lane, such as icing or heavy snow, which can negate all the work of clearing the lane. Under such conditions, takeoff and landing may be impossible.

Visibility is affected fog, rain, snow, dust, smoke, in general, everything that lowers this very visibility. And it is not so important what exactly caused the poor visibility. The main thing is how well the runway is visible in specific conditions.

Here it is still necessary to clarify such a moment as the height of the decision, or, as they say, the point of no return - this is the height to which, when descending, the pilot can still go around. That is, before this altitude, the pilot must decide whether he can land or is forced to climb again.

Wind is a very important factor, influencing the decision "to take off or not to take off". Side wind can be a danger, because to compensate for it you have to turn the plane a little into the wind. And when landing, at the moment of adhesion to the runway, the aircraft must be sharply turned around and directed along the axis of the landing line, which can be difficult to do.

Also great importance has a wind direction. Planes take off and land against the wind. This reduces the takeoff and run distance, that is, it allows you to take off earlier during takeoff or reduce the speed of the aircraft faster during landing.

But there are airports where it is impossible to change the direction of takeoff / landing due to geographical features. For example, on one side of the runway the sea, on the other - the mountains. If the wind blows towards the sea, then it is possible to land (towards the mountains), but it is no longer possible to take off (a tailwind does not make it possible to quickly get off the ground). Therefore, it is sometimes not clear to passengers why some planes fly (that is, they land), while others do not (that is, they do not take off).

There is one more nuance in the question “to fly or not to fly”. All flights are conditionally divided into 2 categories: flight duration up to 2 hours and more than 2 hours. In the first case (for short distances), pilots are allowed to rely on the actual weather and ignore the forecast. In the second option (long distances), they are guided, first of all, by the forecast, and only then they look at the actual weather at the airfield.

The final decision on takeoff and landing is always made by the aircraft commander.

And if he decides not to fly, trust me, it's for your own good.

Don't blame the airline, or the pilots, or the airport, but thank everyone for your life.

Travel safely!

And have a good rest!

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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 fresh water the speed of sound 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 on 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 fastest high speed with which energy and information can move. 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: cruising speed passenger aircraft- 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 maximum speeds from 36 to 122 meters per second, that is, from 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 collisions can withstand spacesuits, as well as skins and other parts of the spacecraft, for example fuel tanks And solar panels testing them for strength. To do this, spacesuits and skin are subjected to impacts with various objects from a special installation with supersonic speeds exceeding 7500 meters per second.

Wind is the movement of air in a horizontal direction along the earth's surface. In which direction it blows depends on the distribution of pressure zones in the planet's atmosphere. The article deals with issues related to the speed and direction of the wind.

Perhaps, absolutely calm weather will be a rare phenomenon in nature, since you can constantly feel that a light breeze is blowing. Since ancient times, mankind has been interested in the direction of air movement, so the so-called weather vane or anemone was invented. The device is an arrow freely rotating on a vertical axis under the influence of wind force. She points his direction. If you determine the point on the horizon from which the wind blows, then the line drawn between this point and the observer will show the direction of air movement.

In order for an observer to convey information about the wind to other people, concepts such as north, south, east, west and their various combinations are used. Since the totality of all directions forms a circle, the verbal formulation is also duplicated by the corresponding value in degrees. For example, north wind means 0 o (the blue compass needle points due north).

The concept of the wind rose

Speaking about the direction and speed of movement of air masses, a few words should be said about the wind rose. It is a circle with lines showing how air flows. The first mention of this symbol was found in the books of the Latin philosopher Pliny the Elder.

The entire circle, reflecting the possible horizontal directions of the forward movement of air, is divided into 32 parts on the wind rose. The main ones are north (0 o or 360 o), south (180 o), east (90 o) and west (270 o). The resulting four parts of the circle are divided further, forming the northwest (315 o), northeast (45 o), southwest (225 o) and southeast (135 o). The resulting 8 parts of the circle are again divided in half each, which forms additional lines on the wind rose. Since the result is 32 lines, the angular distance between them is equal to 11.25 o (360 o /32).

Note that a distinctive feature of the wind rose is the image of a fleur-de-lis located above the north icon (N).

Where does the wind blow from?

Horizontal movements of large air masses are always carried out from areas of high pressure to areas of lower air density. At the same time, it is possible to answer the question of what wind speed is by examining the location on the geographical map of isobars, that is, wide lines within which air pressure is constant. The speed and direction of movement of air masses is determined by two main factors:

• The wind always blows from the areas where the anticyclone stands to the areas covered by the cyclone. This can be understood if we remember that in the first case we are talking about zones of high pressure, and in the second case - low pressure.
• Wind speed is in direct proportion to the distance that separates two adjacent isobars. Indeed, the greater this distance, the weaker the pressure drop will be felt (in mathematics they say a gradient), which means that the forward movement of air will be slower than in the case of small distances between isobars and large pressure gradients.

Factors affecting wind speed

One of them, and the most important one, has already been voiced above - this is the pressure gradient between neighboring air masses.

In addition, the average wind speed depends on the topography of the surface over which it blows. Any irregularities in this surface significantly hinder the forward movement of air masses. For example, everyone who has been in the mountains at least once should have noticed that the winds are weak at the foot. The higher you climb the mountainside, the stronger the wind is felt.

For the same reason, winds blow stronger over the sea than over land. It is often eroded by ravines, covered with forests, hills and mountain ranges. All these heterogeneities, which are not over the seas and oceans, slow down any gusts of wind.

High above the earth's surface (on the order of several kilometers) there are no obstacles to the horizontal movement of air, so the wind speed in the upper troposphere is high.

Another factor that is important to consider when talking about the speed of movement of air masses is the Coriolis force. It is generated due to the rotation of our planet, and since the atmosphere has inertial properties, any movement of air in it is deflected. Due to the fact that the Earth rotates from west to east around its own axis, the action of the Coriolis force leads to the deviation of the wind to the right in the northern hemisphere, and to the left in the southern.

Curiously, this effect of the Coriolis force, which is negligible at low latitudes (tropics), has a strong influence on the climate of these zones. The fact is that the slowdown in wind speed in the tropics and at the equator is compensated by increased updrafts. The latter, in turn, lead to the intense formation of cumulus clouds, which are sources of strong tropical showers.

Instrument for measuring wind speed

It is an anemometer, which consists of three cups located at an angle of 120 o relative to each other, and fixed on a vertical axis. The principle of operation of an anemometer is quite simple. When the wind blows, the cups experience its pressure and begin to rotate on the axis. The stronger the air pressure, the faster they spin. By measuring the speed of this rotation, one can accurately determine the wind speed in m/s (meters per second). Modern anemometers are equipped with special electrical systems that independently calculate the measured value.

The instrument of wind speed based on the rotation of the cups is not the only one. There is another simple tool called the pitot tube. This device measures the dynamic and static wind pressure, the difference between which can accurately calculate its speed.

Beaufort scale

Information about wind speed, expressed in meters per second or kilometers per hour, for most people - and especially for sailors - says little. Therefore, in the 19th century, the English admiral Francis Beaufort proposed to use some empirical scale for evaluation, which consists of a 12-point system.

The higher the Beaufort scale, the stronger the wind blows. For example:

• The number 0 corresponds to absolute calm. With it, the wind blows at a speed not exceeding 1 mph, that is, less than 2 km / h (less than 1 m / s).
• The middle of the scale (number 6) corresponds to a strong breeze, the speed of which reaches 40-50 km/h (11-14 m/s). Such a wind is capable of raising large waves on the sea.
• The maximum on the Beaufort scale (12) is a hurricane whose speed exceeds 120 km/h (more than 30 m/s).

Major winds on planet Earth

They are usually classified into one of four types in the atmosphere of our planet:

• Global. They are formed as a result of the different ability of continents and oceans to heat up from the sun's rays.
• Seasonal. These winds change with the season of the year, which determines how much solar energy a certain area of ​​the planet receives.
• Local. They are associated with the features of the geographical location and topography of the area under consideration.
• Rotating. These are the strongest movements of air masses that lead to the formation of hurricanes.

Why is it important to study the winds?

In addition to the fact that information about wind speed is included in the weather forecast, which every inhabitant of the planet takes into account in his life, air movement plays an important role in a number of natural processes.

So, he is a carrier of plant pollen and is involved in the distribution of their seeds. In addition, wind is one of the main sources of erosion. Its destructive effect is most pronounced in deserts, when the terrain changes dramatically during the day.

We should also not forget that the wind is the energy that people use in economic activities. According to general estimates, wind energy makes up about 2% of all solar energy falling on our planet.