WHAT IS AN ANEMOSCOPE OR WIND SOCK? - SCIENCE - 2024

An anemoscope, also known as a windsock or wind cone, is an instrument used to measure wind speed and strength. Wind is usually defined according to two essential parameters, namely direction and speed.

When measuring the direction of air currents, the weather vane is often used. Whereas, if you want to know the wind speed, using the anemoscope is the right thing to do.

Wind cone or anemoscope

It should be noted that wind speed is also usually measured by anemometers or anemographs, instruments that have a device inside capable of recording, graphically or digitally, the wind speed.

Windsocks or anemometers are a type of anemometer and their objective is to inform at what speed and force the air currents move in order to know how they will affect our daily life, especially in the fields of meteorology and aeronautics.

Wind speed is always fluctuating due to differences in temperature when uneven heating occurs in various areas of the earth and the atmosphere.

Masses of hot air tend to descend and their place is occupied by masses of cold and dense air, causing air currents.

The wind is altered by the relief and the acceleration of the Coriolis effect, caused by the movement of the Earth's rotation, and it is up to the anemoscope to estimate the speed of its currents.

Origins of the anemoscope

Its origins date back to 1732 when the French engineer Henri Pitot designed his famous “Pitot Tube”.

This tube served, at first, to calculate the speed of a fluid in a pipe until later it became an elementary instrument for measuring air speed.

The object of the apparatus was to calculate the stagnation pressure, by comparing the pressure exerted by the air impacting one side of the tube with the normal atmospheric pressure obtained by the wind speed.

In the image you can see how its structure is similar to the current windsock.

Pitot tube

Physical description of the anemoscope

The anemoscope consists of a tube or cloth sleeve in the shape of a truncated cone, with two perforated ends.

One end of the cone, the widest part, is attached to a vertical mast that has a metal ring, which allows the sleeve to always remain open.

The circle or metal ring is associated with a mechanism that allows it to rotate 360 ​​degrees to indicate the direction of the wind and orient the sleeve freely in any direction.

The size of the sleeve usually varies depending on the place where it is intended to be installed and the visibility required, however, they generally reach 1 to 4 meters in length. With a diameter of 30 to 90 centimeters at its widest part.

Its design usually includes two striking colors, red and white being common, which are distributed in 5 sections of the sleeve, narrowing towards the end where the wind will originate.

Each of these five sections represents 3 knots, that is, about 5.5 kilometers per hour. Hence, if it is observed that the beam rises only in the first initial section in red, as shown in the image below, a speed of 3 knots will be reported.

And, if the sleeve is stretched reaching a completely horizontal position, it can be spoken of a wind speed of up to 15 knots or more.

How does an anemoscope work?

As air enters the sleeve, it rotates allowing air to pass through the larger opening. And, depending on the force of the wind, the sleeve will tilt upwards as it fills with air and can reach its maximum point when it occupies a completely horizontal position with respect to the mast.

It should be noted that the direction of the wind will be opposite to the direction in which the sleeve is pointing. Hence, if a windsock points south, the wind will actually come from the north.

The wind speed will always be reflected in the angle formed by the beam with respect to the mast.

And, although the position of the sleeve does not inform about the exact speed of the wind, it is a fairly accurate indicator depending on the inclination of the sleeve and the thickness of its interior.

1- Inclination of the windsock

The sleeve will provide the following information depending on the angle it forms:

-If the cone reaches a vertical position, the wind speed will be considered smooth and calm.

-If the cone reaches an inclination of 45 degrees, it will speak of a considerable wind speed.

-If the cone reaches an inclination of 90 degrees, the wind speed will be considered strong.

two-

This meteorological apparatus works through the principle of compression.

Compressive stress is understood as the result of stresses or pressures that are generated in a continuous medium or a deformable solid.

Hence, said deformable solid is the sleeve and when the wind enters it, the compression principle acts forcing the sleeve to straighten, which causes it to rise as the wind speed is higher.

Uses of the anemoscope

It is commonly used in the field of meteorology and air navigation.

Windsocks are useful in airports, heliports, airfields, viaducts that are located at high altitudes, and some roads.

They are intended to indicate to drivers the wind speed they are facing and to take precautions.

Likewise, they are often used in industrial areas where chemical products are handled, which run the risk of falling or mixing depending on the air currents that approach them.

Lately, they have been put into practice on golf courses, and they have begun to be illuminated in airports at night.

References

1. What is the anemometer? Retrieved on August 24, 2017 from oni.escuelas.edu.ar
2. How is wind speed and direction measured? Retrieved on August 24, 2017 from profesaulosuna.com.
3. How to interpret a windsock. Retrieved on August 24, 2017 from siempreenlasnubes.com.
4. Wind. Retrieved on August 24, 2017 from senamhi.gob.pe.
5. The purpose of windsocks. Retrieved on August 24, 2017 from wordpress.com.
6. Pitot tube. Retrieved on August 24, 2017 from ecured.cu.