Wind force in points: maximum, minimum, Beaufort scale and classification

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Wind force in points: maximum, minimum, Beaufort scale and classification
Wind force in points: maximum, minimum, Beaufort scale and classification

Each natural phenomenon, which has different degrees of severity, is usually evaluated 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 (emphasis 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, remaining relevant to this day.

The cloth flutters in the wind

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. Directionmovement always comes from a higher area.

The following characteristics are commonly used to describe the wind:

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

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

wind force in points and m s

The direction of the wind is determined by the side of the world from where the movement began (from the north - the north wind, etc.). 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 rapid movement of air masses above the earth's surface.

Features of wind measurement

In order to correctly correlate weather data with your real position or to correctly measure, you need to know what standard conditions professionals use.

  • Measuring the strength and speed of the wind takes place at a height of ten meters in an openflat surface.
  • The name of the direction of the wind gives the cardinal direction from which it blows.

Managers of 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 wind force in points, is given for the open sea. It will be much less in shallow water areas and coastal zones.

Calm on the sea

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 Arctic Ocean, washing Canada and Alaska, bears his name. An Antarctic island is named after Beaufort.

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

wind force in beaufort

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 were added to the Beaufort scaleimprovements - the ratio of points and a verbal description of the manifestation of the elements with the speed of the wind (1926), and five more divisions were added - gradation points for the strength of hurricanes (USA, 1955).

Strong wind

Criteria for estimating wind strength in Beaufort points

In its modern form, the Beaufort scale has several characteristics that allow, in combination, to most accurately correlate a specific atmospheric phenomenon with its indicators in points.

  • Firstly, this is verbal information. A 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, determined by typical manifestations.

Not dangerous wind

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



Wind speed (m/s)

Wind speed (km/h)

Wind speed (sea strands)




Calm, no wind (Calm)

0-0, 2

less than 1 km/h

up to 1 knot

Smoke movement - vertically up, tree leaves do not move

The surface of the sea is immovable, smooth


Light Air

0, 3-1, 5



Smoke has a small angle of inclination, the weather vane is motionless

Slight ripples without foam. Waves no higher than 10 centimeters


Light Breeze

1, 6-3, 3



Feel the breath of the wind on the skin of the face, there is movement and rustle of leaves, a slight movement of the weather vane

Short low waves (up to 30 centimeters) with a glass-like crest


Gentle Breeze

3, 4-5, 4



The continuous movement of foliage and thin branches on the trees, the waving of flags

Waves stay short but more visible. The ridges begin to tip over and turn into foam. Rare small "lambs" appear. The height of the waves reaches 90 centimeters, but on average does not exceed 60


Moderate Breeze

5, 5-7, 9



Begins to rise from the ground dust, small debris

Waves become longer and rise up to one and a half meters. "Lambs" appear often

Borderline can be called a wind of 5 points, characterized as "fresh", or fresh breeze. 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. Splashes occasionally appear.

Fresh wind in the field

Wind Bringing Trouble

Strong phenomena begin with a force of 6 winds that can cause damage to he alth and property.



Wind speed (m/s) Wind speed (km/h) Wind speed (sea strands) Description



Strong Breeze

10, 8-13, 8



Thick tree branches sway violently, the hum of telegraph wires can be heard

Formation of large waves, foam crests acquire significant volume, splashing is likely. The average wave height is about three meters, the maximum reaches four


Moderate gale

13, 9-17, 1



The whole tree sways

Active movement of waves up to 5.5 meters high overlapping each other, dispersion of foam along the wind line


Very strong (Gale)

17, 2-20, 7



Tree branches break from the pressure of the wind, foot movement against its direction is difficult

Waves of significant length and height: average - about 5.5 meters, maximum - 7.5 m. Moderately high long waves. Sprays fly up. Foam falls in stripes, the vector coincides with the direction of the wind


Storm (Strong gale)

20, 8-24, 4



Wind damages buildings, starts to break roof tiles

Waves up to ten meters with an average height of up to seven. The streaks of foam become wider. Tilting combs splatter. Reduced visibility

Dangerous wind power

Wind force ten to twelve is dangerous and is characterized as a strong (storm) and violent 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 a dangerous height even for large ships - from nine meters and above. Foam covers the water surface, visibility is zero or close to that.

The wind hinders walking

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 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 strengths from 13 to 17 inclusive are refinements for destructive hurricane winds and their associated environmental phenomena.

wind force 12

How to protect yourself when the elements are raging?

If the storm warning of the Ministry of Emergency Situations catches in the open, 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, keep pets safe.

If a heavy wind catches in a fragile building - 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.

People go against strong wind

In nature, you need to take a place away from tall trees, power lines. Tents will be safer in the undergrowth.

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

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