Hurricane wind is considered at speed. Thunderstorm is not a hindrance to flight. Basic wind parameters

Each a natural phenomenon having different degrees severity, it is customary to evaluate in accordance with certain criteria. Especially if information about it must be transmitted quickly and accurately. For wind strength, the Beaufort scale has become a single international benchmark.

Developed by the British rear admiral, a native of Ireland, Francis Beaufort (stress falls on the second syllable) in 1806, the system, improved in 1926 by adding information about the equivalence of wind strength in points of its specific speed, allows you to fully and accurately characterize this atmospheric process, while remaining relevant and to this day.

What is wind?

Wind is the movement of air masses parallel to the surface of the planet (horizontally above it). This mechanism is caused by pressure difference. The direction of movement always comes from the higher area.

To describe the wind, it is customary to use the following characteristics:

• speed (measured in meters per second, kilometers per hour, knots and points);
• wind strength (in points and m.s. - meters per second, the ratio is approximately 1:2);
• direction (according to cardinal directions).

The first two parameters are closely related. They can be mutually denoted by each other's units of measurement.

The direction of the wind is determined by the side of the world from where the movement began (from the north - North wind and so on.). Velocity determines the pressure gradient.

Baric gradient (otherwise - barometric gradient) - change in atmospheric pressure per unit distance along the normal to a surface of equal pressure (isobaric surface) in the direction of decreasing pressure. In meteorology, the horizontal barometric gradient is usually used, that is, its horizontal component (Great Soviet Encyclopedia).

The speed and strength of the wind cannot be separated. A large difference in indicators between atmospheric pressure zones generates a strong and fast moving air masses above the earth's surface.

Features of wind measurement

In order to correctly correlate the data of meteorological services with their real situation or correctly measure, you need to know what standard conditions professionals use.

• The measurement of the strength and speed of the wind takes place at a height of ten meters on an open flat surface.
• The name of the wind direction is given by the cardinal direction from which it blows.

Managers water transport, as well as lovers of spending time in nature, often purchase anemometers that determine the speed, which is easy to correlate with the wind force in points. There are waterproof models. For convenience, devices of various compactness are produced.

In the Beaufort system, the description of the height of the waves, correlated with a certain force of wind in points, is given for the open sea. It will be much less in shallow water areas and coastal zones.

From personal to global use

Sir Francis Beaufort not only had a high military rank in the navy, but was also a successful practical scientist who held important posts, a hydrographer and cartographer, who brought great benefits to the country and the world. One of the seas in the North bears his name. Arctic Ocean bordering Canada and Alaska. An Antarctic island is named after Beaufort.

A convenient system for estimating wind strength in points, available for fairly accurate determination of the severity of the phenomenon "by eye", Francis Beaufort created for his own use in 1805. The scale had a gradation from 0 to 12 points.

In 1838, the system of visual assessment of weather and wind strength in points began to be officially used by the British Navy. In 1874 it was adopted by the international synoptic community.

In the 20th century, several more improvements were made to the Beaufort scale - the ratio of points and a verbal description of the manifestation of the elements with wind speed (1926), and five more divisions were added - gradation points for the strength of hurricanes (USA, 1955).

Criteria for estimating wind strength in Beaufort points

IN modern form The Beaufort scale has several characteristics that allow, in combination, to most accurately correlate a specific atmospheric phenomenon with his scores.

• First, it is verbal information. Verbal description of the weather.
• Average speed in meters per second, kilometers per hour and knots.
• The impact of moving air masses on characteristic objects on land and sea is determined by typical manifestations.

Non-dangerous wind

Safe wind is determined in the range from 0 to 4 points.

A wind of 5 points, characterized as "fresh", or fresh breeze, can be called borderline. Its speed ranges from 8 to 10.7 meters per second (29-38 km/h, or 17 to 21 knots). Thin trees sway along with the trunks. Waves rise up to 2.5 (average up to two) meters. Sometimes there are splashes.

Wind that brings trouble

With a wind force of 6 points, strong phenomena begin that can cause damage to health and property.

Dangerous force of the wind

Wind force from ten to twelve points is dangerous and is characterized as a strong (storm) and severe storm (violent storm), as well as a hurricane (hurricane).

Wind uproots trees, damages buildings, destroys vegetation, destroys buildings. The waves make a deafening noise from 9 meters and above, long. At sea they reach dangerous heights even for large ships- from nine meters and above. Foam covers the water surface, visibility is zero or close to such an indicator.

The speed of movement of air masses is from 24.5 meters per second (89 km / h) and reaches from 118 kilometers per hour with a wind force of 12 points. Violent storms and hurricanes (winds of magnitudes 11 and 12) are very rare.

Additional five points to the classical Beaufort scale

Since hurricanes are also not identical to each other in terms of intensity and degree of damage, in 1955 the United States Weather Bureau adopted an addition to the standard Beaufort classification in the form of five scale units. Wind strength from 13 to 17 points inclusive - these are clarifying characteristics for destructive hurricane winds and related events environment.

How to protect yourself when the elements are raging?

If the storm warning of the Ministry of Emergency Situations catches in an open area, it is better to follow the advice and reduce the risk of accidents.

First of all, you should pay attention to warnings every time - there is no guarantee that the atmospheric front will come to the area where you are, but you also cannot be sure that it will bypass it again. All items should be removed or securely fastened, to protect pets.

If a heavy wind catches in a fragile structure - a garden house or other light structures - it is better to close the windows from the air movement side, and if necessary, strengthen them with shutters or boards. On the leeward, on the contrary, slightly open and fix in this position. This will eliminate the danger of an explosive effect from the pressure difference.

It is important to remember that any strong wind can bring unwanted precipitation - in winter it is snowstorms and snowstorms, in summer dust and sand storms are possible. It should also be borne in mind that strong winds can occur even in absolutely clear weather.

Many people ask the question: at what wind speed do planes not fly? Indeed, there are certain speed limits. Compared to the speed of the aircraft, which reaches 250 m/s, even a strong wind with a speed of 20 m/s will not interfere with the aircraft during flight. However, a crosswind can interfere with an airliner when it is moving at a slower speed, namely at the time of takeoff or landing. Therefore, under such conditions, planes do not take off. Air currents affect the speed of the aircraft, the direction of movement, as well as the length of the roll and takeoff run. In the atmosphere, these streams are present at all altitudes. This movement of air in relation to a flying airliner is a portable movement. If a strong wind is blowing, the direction of movement of the airliner in relation to the ground does not coincide with the longitudinal axis of the aircraft. Strong air currents can blow the plane off course.

Airliners always land and take off against the direction of the wind. In the case of takeoff or landing with a tailwind, the length of the takeoff run and run increases significantly. When taking off or landing, an airliner penetrates the lower atmosphere so quickly that the pilot does not have time to respond to a change in the wind. If he does not know about a sharp increase or, conversely, a weakening of air flows in the lower layers of the atmosphere, this is fraught with a plane crash.

During takeoff, when an airliner is gaining altitude, it enters a zone of strong headwind. As the aircraft climbs, the lift force of the aircraft increases. Moreover, the increase occurs faster than the pilot can control it. The flight path in this case may be higher than the calculated one. If there is a sharp increase in wind, this can cause the airliner to fall into a supercritical angle of attack. This can lead to airflow stall and collision with the ground.

Generally, the allowable maximum wind force is determined for each aircraft individually, depending on the specifics of its specific characteristics and technical capabilities. Sets the maximum wind speed at which takeoff or landing can be made, by the manufacturer of the airliner. More precisely, the manufacturer sets two maximum speeds: passing and lateral. Tail speed for most modern airliners is the same. During takeoff and landing, the tail speed must not exceed 5 m/s. As for the lateral speed, it is different for each airliner:

• for TU-154 aircraft - 17 m/s;
• for AN-24 - 12 m/s;
• for TU-134 - 20 m/s.

On average, airliners are set to the maximum lateral speed 17 m/s. At more speed the vast majority of aircraft do not take off. If there is a sharp increase in wind in the arrival area, the speed of which exceeds the permissible values, the planes do not land at this airport, but make emergency landing to another runway where conditions allow the aircraft to land safely.

Answering the question in what wind the planes do not fly, it can be said with confidence that at a speed of more than 20 m / s, if the wind blows perpendicular to the runway, takeoff cannot be carried out. Such a strong wind is associated with the passage of powerful cyclones. Below you can watch a video of landing an aircraft in a strong crosswind to see how difficult it is to do even for a professional experienced pilot with a long experience. Of particular danger in this case is the gusty wind in the lower layers of the atmosphere. It can begin to blow at the most inopportune moment, forming a large roll, which poses a great danger to the aircraft.

Crosswind is dangerous because it requires the pilot to take certain actions that are very difficult to perform. In aviation, there is such a thing as a "drift angle". This term refers to the amount of angle an airliner deviates from a given direction due to the wind. The stronger the wind, the larger this angle. Accordingly, the more effort the pilot needs to make to turn the airliner to this angle in reverse side. As long as the aircraft is in flight, even such a strong wind does not cause any problems. But as soon as the plane makes contact with the surface of the runway, the airliner acquires traction and begins to move in a direction parallel to its axis. At this moment, the pilot must abruptly change the direction of the aircraft, which is very difficult.

As for the problem of a strong tailwind, it is easily solved by changing the operating threshold of the runway. However, not every airport has such an opportunity. For example, Sochi and Gelendzhik are deprived of such an opportunity. If a strong wind blows towards the sea, landing can be carried out, but taking off under such conditions is unsafe. That is, the landing of the aircraft at strong wind possible, but not in all cases.

Runway condition

Even if the wind speed allows you to take off or land, there are still a number of factors that can affect the final decision. In particular, in addition to weather conditions, visibility, the condition of the runway is taken into account. If it is covered with ice, landing or takeoff cannot be carried out. In aviation, there is such a term as "traction coefficient". If this indicator is below 0.3, this runway strip unsuitable for landing or takeoff and needs to be cleaned. If the decrease in friction coefficient was due to heavy snowfall, in which cleaning is not possible, the entire airport is closed until the weather improves. Such a break in work can last several hours.

How is the decision to take off made?

This decision must be made by the aircraft commander. To do this, first of all, he must familiarize himself with the meteorological data on the air hubs of departure, landing and alternate airports. For this, METAR and TAF forecasts are used. The first forecast is issued for all airports every half hour. The second is given every 3-6 hours. Such forecasts reflect all relevant information that may influence the decision to take off or cancel a flight. In particular, such forecasts contain data on wind speed and its changes.

To make a decision, all flights are conditionally divided into 2-hour and longer ones. If the flight lasts less than two hours, it is enough for the actual weather to be acceptable (above the minimum) for takeoff. If the flight is longer, the TAF forecast must be additionally taken into account. If the weather conditions at the destination do not allow landing, in some cases, the decision to take off may be positive. For example, if the weather conditions at the destination are below the minimum, however, there are two aerodromes in the immediate vicinity with optimal weather conditions. But a positive decision is almost never made in these cases, given the danger of such a flight.

In contact with

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.

Besides average speed wind 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.

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.

Beaufort scale- a conditional scale for visual assessment of the strength (speed) of the wind in points according to its effect on ground objects or on waves at sea. It was developed by the English Admiral F. Beaufort in 1806 and at first was used only by him. In 1874, the Standing Committee of the First Meteorological Congress adopted the Beaufort scale for use in international synoptic practice. In subsequent years, the scale has changed and refined. The Beaufort scale is widely used in marine navigation.