A device for measuring wind speed. Meteorological instrument. How are wind speed and direction measured? Measuring wind speed with an anemometer

Beaufort scale- a conventional scale for visually assessing the strength (speed) of the wind in points based on its effect on ground objects or on sea waves. 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 was changed and refined. The Beaufort scale is widely used in maritime navigation.

Wind power earth's surface Beaufort scale (at a standard height of 10 m above an open, level surface)
Beaufort points	Verbal definition of wind force	Wind speed, m/sec	Wind action
			on the land	on the sea
0	Calm	0-0,2	Calm. Smoke rises vertically	Mirror smooth sea
1	Quiet	0,3-1,5	The direction of the wind is noticeable from the drift of the smoke, but not from the weather vane.	Ripples, no foam on the ridges
2	Easy	1,6-3,3	The movement of the wind is felt by the face, the leaves rustle, the weather vane is set in motion	Short waves, crests do not capsize and appear glassy
3	Weak	3,4-5,4	The leaves and thin branches of the trees sway all the time, the wind flutters the upper flags	Short, well defined waves. The ridges, overturning, form a glassy foam, occasionally small white lambs are formed
4	Moderate	5,5-7,9	The wind raises dust and pieces of paper and moves thin tree branches.	The waves are elongated, white caps are visible in many places
5	Fresh	8,0-10,7	Thin tree trunks sway, waves with crests appear on the water	Well developed in length, but not very large waves, white caps are visible everywhere (in some cases splashes are formed)
6	Strong	10,8-13,8	Thick tree branches sway, telegraph wires hum	Large waves begin to form. White foamy ridges occupy large areas (splashes are likely)
7	Strong	13,9-17,1	The tree trunks are swaying, it’s difficult to walk against the wind	The waves pile up, the crests break off, the foam lies in stripes in the wind
8	Very strong	17,2-20,7	The wind breaks tree branches, it is very difficult to walk against the wind	Moderately high long waves. Spray begins to fly up along the edges of the ridges. Strips of foam lie in rows in the direction of the wind
9	Storm	20,8-24,4	Minor damage; the wind tears off smoke hoods and tiles	High waves. The foam falls in wide dense stripes in the wind. The crests of the waves begin to capsize and crumble into spray, which impairs visibility
10	Heavy storm	24,5-28,4	Significant destruction of buildings, trees are uprooted. Rarely happens on land	Very high waves with long, downward-curving crests. The resulting foam is blown away by the wind in large flakes in the form of thick white stripes. The surface of the sea is white with foam. The strong roar of the waves is like blows. Visibility is poor
11	Fierce Storm	28,5-32,6	Large destruction over a large area. Very rarely observed on land	Exceptionally high waves. Small and medium-sized vessels are sometimes hidden from view. The sea is all covered with long white flakes of foam, located downwind. The edges of the waves are blown into foam everywhere. Visibility is poor
12	Hurricane	32.7 or more		The air is filled with foam and spray. The sea is all covered with stripes of foam. Very poor visibility

Wind as a natural phenomenon has been known to everyone since early childhood. It pleases with a fresh breeze on a hot day, drives ships across the sea, and can even bend trees and break roofs on houses. The main characteristics that determine the wind are its speed and direction.

WITH scientific point sight, wind is called movement air masses in the horizontal plane. This movement occurs because there is a difference atmospheric pressure and heat between two points. Air moves from areas high pressure to areas where the pressure level is lower. As a result, wind arises.

Wind characteristics

In order to characterize the wind, two main parameters are used: direction and speed (force). The direction is determined by the side of the horizon from which it blows. It can be indicated in points, in accordance with the 16-point scale. According to it, the wind can be north, southeast, north-northwest, and so on. can also be measured in degrees, relative to the meridian line. On this scale, north is defined as 0 or 360 degrees, east as 90 degrees, west as 270 degrees, and south as 180 degrees. In turn, they are measured in meters per second or in knots. A knot is approximately 0.5 kilometers per hour. Wind strength is also measured in points, according to the Beaufort scale.

According to which the wind force is determined

This scale was introduced in 1805. And in 1963, the World Meteorological Association adopted a gradation that is still in effect today. Within its framework, 0 points corresponds to calm, in which the smoke will rise vertically and the leaves on the trees will remain motionless. A wind force of 4 corresponds to a moderate wind, in which small waves form on the surface of the water and thin branches and leaves on trees can sway. 9 points correspond to a storm wind, in which even big trees, tiles are torn off roofs, high waves rise on the sea. And the maximum wind force in accordance with this scale, namely 12 points, occurs in a hurricane. This is a natural phenomenon in which the wind causes serious damage; even permanent buildings can collapse.

Harnessing the power of the wind

Wind power is widely used in the energy sector as one of the renewable natural sources. Since time immemorial, humanity has been using this resource. Suffice it to recall sailing ships. Windmills, with the help of which wind is converted for further use, are widely used in those places characterized by constant strong winds. From various areas application of such a phenomenon as wind power, it is also worth mentioning the wind tunnel.

Wind - a natural phenomenon, which can bring pleasure or destruction, as well as be useful to humanity. And its specific action depends on how great the strength (or speed) of the wind turns out to be.

The speed of movement of air currents can most successfully be measured using a wind meter ( anemometer). The cup anemometer has become widespread - measuring device, on the vertical axis of which cups are cross-shaped - hemispheres, which rotate from any, even light, breeze, and the stronger it is, the faster the rotation occurs. From the axis of the device there is a transmission to the revolution counter.

The best known wind gauge is the cup anemometer.
How more speed wind, the faster it rotates the cups.

A weather vane is usually installed next to wind gauges, indicating the direction of the wind. At airfields and near bridges, where the wind can be dangerous for cars, wind direction indicators are installed - large cone-shaped bags made of striped fabric, open on both sides.

At airfields and near bridges, the direction and strength of the wind is shown from afar
windsocks are large striped canvas cones open at both ends.

Before people learned to measure wind speed in m/sec or km/h, they used the Beaufort scale for this purpose - the English admiral, who compiled a table that described and characterized different winds, summarized in a point system from 0 (complete calm) to 12 points (the strongest hurricane winds, reaching speeds of 117 km/h). However, during tornadoes and tropical cyclones its speed is even greater.

Vane

For the experience you need:

Long nail
- wooden pole
- wooden beads
- plywood
- hammer
- ruler
- shoe knife
- wood glue
- compass

1. Cut out the parts shown in the drawing below from plywood. The width of the slots should be equal to the thickness of the plywood.

2. Assemble the weather vane as shown in the picture. Secure the parts together with glue.

3. Balance the vane on the nail head to find its center. Drive a nail in this place, stringing a bead on it on both sides of the weather vane, as shown in the figure. The weather vane must be mounted on a pole so that it can rotate freely.

4. Using a weather vane, determine the direction of the wind. His nose indicates the direction from which the wind is blowing. The wind from the south is called the south wind.

Anemometer

For the experience you need:

Tea spoon
- screwdriver
- wire
- large screw
- a sheet of plywood measuring approximately 20x25 cm
- permanent marker
- ruler
- nails or screws

1. Drive a screw into the upper left corner of the plywood about 2.5 cm from the edges.

2. Wrap the wire around the handle of the spoon and the screw, as in the picture. The spoon should swing freely on the wire.

3. Using a ruler, draw a scale on the plywood and mount the anemometer on a fence or pole.

The higher the spoon tilts, the stronger the wind.

IA website.

Beaufort scale

0 points - calm
Mirror-smooth sea, almost motionless. The waves practically do not run onto the shore. The water looks more like a quiet lake backwater than sea ​​coast. There may be haze over 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/hour.

1 point - quiet
There are light ripples on the sea. The height of the waves reaches up to 0.1 meters. The sea can still merge with the sky. You can feel 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 wind, the weather vane begins to move.

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

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

5 points - fresh
Almost the entire sea is covered with whitecaps. 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 and thick tree branches bend, telephone wires hum.

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

8 points - very strong
Strong waves, foam on every crest. The height of the waves reaches 7.5 meters, the average height is 5.5 meters. Wind speed 17.2 - 20 m/s. Walking against the wind is difficult, talking is almost impossible. 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 tears off poorly reinforced roof coverings.

10 points - severe storm
Sea white. The waves crash onto the shore or against the rocks with a roar. Maximum height waves 12 meters, average height 9 meters. The wind, with a speed of 24.5 - 28.4 m/s, tears off roofs and causes significant damage to buildings.

11 points - severe 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 permanent structures. The wave height is more than 16 meters.

Sea state scale

Unlike the generally accepted twelve-point wind rating system, there are several ratings of sea waves. The generally accepted ones are British, American and Russian assessment systems. All scales are based on a parameter that determines the average height of significant waves (according to the website savelyev.info). This parameter is called Significance Wave Height (SWH). In the American scale, 30% of significant waves are taken, in the British 10%, in the Russian 3%. The height of the wave is calculated from the crest (the highest point of the wave) to the trough (the base of the trough).

Below is a description of wave heights:

• 0 points - calm,
• 1 point - ripple (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 seas (SWH 2.5 - 4.0 m),
• 6 points - very rough seas (SWH 4.0 - 6.0 m),
• 7 points - strong waves (SWH 6.0 - 9.0 m),
• 8 points - very strong waves (SWH 9.0 - 14.0 m),
• 9 points - phenomenal waves (SWH > 14.0 m).

The word "storm" does not apply in this scale. Since it determines not the strength of the storm, but the height of the wave. A storm is defined by Beaufort.
For the WH parameter for all scales, it is precisely part of the waves that is taken (30%, 10%, 3%) 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 had its own SWH value, where a certain percentage of the highest waves is taken. There are no instruments to measure wave height. That's why no precise definition points. 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.

Visual range scale

Visibility is the maximum distance at which objects can be 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 conventional scale of points.

This scale is a way of indicating the transparency of the atmosphere.

There are day and night visibility ranges.

Below is the daily visual range scale.

Up to 1/4 cable
About 46 meters. Very poor visibility. Dense fog or snowstorm.
Up to 1 cable
About 185 meters. Bad visibility. Thick fog or wet snow.
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, haze, rain.
2 - 5 miles
3.7 - 9.5 km. Light haze, haze, light rain.
5 - 11 miles
9.3 - 20 km. Good visibility. The horizon is visible.
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.

1. The emergence of wind. Air is transparent and colorless, but we all know that it exists because we feel its movement. Air is always in motion. Its movement in the horizontal direction is called by the wind.

The cause of wind is the difference in atmospheric pressure over areas of the earth's surface. As soon as the pressure in any area increases or decreases, the air rushes from the place of higher pressure towards the lower one. There are various reasons due to which the balance of atmospheric pressure is disturbed. The main thing is the unequal heating of the earth's surface and the difference in temperatures in different areas.

Let's consider this phenomenon using the example of a breeze that forms on the shore of the sea or a large lake. During the day, the breeze changes its direction twice. This happens due to the difference in temperature and atmospheric pressure over land and water surfaces day and night. Land, unlike the sea, heats up quickly during the day and cools down quickly at night. During the day there is low pressure on land, and high pressure above the water surface; at night it is the other way around. Therefore, the daytime breeze blows from the sea (lake) to the warmer land, and the night breeze blows from the cooler land to the sea (Fig. 20). (Explain the formation of night breeze.) These winds cover a relatively narrow strip of coastline.

2. Wind direction and speed. Wind power. Wind is characterized by direction and speed. The direction of the wind is determined by the side of the horizon from which it blows (Fig. 21). (What is the name of the wind blowing south? west?) Wind speed depends on atmospheric pressure: the greater the pressure difference, the stronger the wind. This wind indicator is affected by friction and air density. At the tops of the mountains the wind gets stronger. Any obstacle (mountain systems and mountain ranges, buildings, forest belts, etc.) affects the speed and direction of the wind. Flowing around an obstacle, the wind in front of it weakens, but on the sides it intensifies. Wind speed increases significantly, for example, between two closely located mountain ranges. (Why is the wind stronger in open areas than in the forest?)

Wind speed is usually measured in meters per second (m/s). The strength of the wind can be assessed by its effect on land objects and the sea in Beaufort scale points (from 0 to 12 points) (Table 1).

Table 1

Beaufort scale for determining wind force

	Meters per second	Wind characteristics	Wind action
			Complete absence of wind. Smoke rises vertically from the chimneys
				The smoke from the chimneys does not rise quite vertically
			The movement of air is felt by the face. Leaves are rustling
			Leaves and small branches sway. Light flags flutter
		Moderate	Thin tree branches sway. The wind raises dust and scraps of paper
			Branches and thin tree trunks sway. Waves appear on the water
			Large branches sway. Telephone wires hum
			Swinging small trees. Foaming waves rise on the sea
			Tree branches break. It's hard to go against the wind
			Minor damage. House pipes and tiles are torn off
			Significant destruction. Trees are uprooted
		Cruel	Great destruction
	more than 32.7		Produces devastating effects

You already know that the speed and direction of the wind are determined by the weather vane (Fig. 22). The weather vane consists of a weather vane, a horizon indicator, a metal plate and an arc with pins. The weather vane rotates freely on a vertical axis and is positioned in the direction of the wind. Using it and the horizon indicator, the wind direction is determined. The wind speed is determined by the deviation of the metal plate from a vertical position to one of the arc pins. The weather vane at meteorological stations is installed at a height of 10-12 m above the earth's surface.

To more accurately measure wind speed, use special device- anemometer (Fig. 23).

The usual wind speed at the earth's surface is 4-8 m/s, and it rarely exceeds 11 m/s (Fig. 24). However, there are winds of destructive force - these are storms (wind speed more than 18 m/s) and hurricanes (more than 29 m/s). Wind speeds in tropical hurricanes reach 65 m/s, and with individual gusts - even up to 100 m/s. Very light wind (with a speed of no more than 0.5 m/s) or calm is called calm . (Under what conditions is calm observed?)

Wind speed, like direction, is constantly changing, both in time and space. The nature of air movement can be seen by watching snowflakes falling in the wind. Snowflakes make random movements: they fly up, then fall, and then describe complex loops.

A visual representation of the frequency of winds for a certain time (month, season, year) gives compass rose(Fig. 25) . It is constructed as follows: eight main directions of the horizon are drawn and the frequency of the corresponding wind is plotted on each according to an accepted scale. For this purpose, average long-term data are taken. The ends of the resulting segments are connected. The repeatability of calms is indicated in the center (circle).

? check yourself

What is wind and how does it arise? What does wind speed depend on? Establish a correspondence between wind speed and its characteristics: 1) 0.6-1.7 m/s a) hurricane 2) more than 29.0 m/s b) calm wind 3) 9.9-12.4 m/s c) strong wind d) light wind Determine where and where the wind will blow: 775 mm 761 mm 753 mm 760 mm 748 mm 758 mm *Where do you think the wish “Tailwind!” came from? *Using the figure “Wind Rose for Minsk”, determine the prevailing winds for our capital. Consider in which part of the city or its surroundings it is best to build industrial enterprises to maintain clean air in the city. Justify your answer. Practical task Construct a wind rose based on the following data for January (the frequency of winds is indicated in%): S-7, S-E-6, E-11, S-E-10, S-13, S-W-20, W-18, N -Z-9, Calm-6.

This is interesting

Strong winds cause great destruction on land and rough seas. In powerful atmospheric vortices (tornadoes), the wind speed reaches 100 m/s. They lift and move cars, buildings, bridges. Particularly destructive tornadoes are observed in the USA (Fig. 26). Every year there are from 450 to 1500 tornadoes with an average death toll of about 100 people.