Anemometer: Working, Types and Applications

An anemometer is a device used to measure the speed of airflow in the atmosphere, wind tunnels, and other gas-flow applications.

• It is a commonly used device in weather stations.
• The name anemometer is derived from the Greek word anemos, which means wind.
• It was first introduced in 1450 by Leon Battista Alberti, an Italian artist and architect.
• Anemometer is an essential tool for meteorologists for studying weather patterns. 
• The commonly used anemometer for wind-speed measurements a the revolving-cup electric anemometer.
• Air pressure can also be used to calculate wind speed.
• A tube anemometer measures wind pressure or speed using air pressure.

Read More: Movement of Air

Key Terms: Anemometer, Wind, Wind Speed, Pressure, Weather, Atmosphere, Vane, Hot Wire, Laser Doppler, Ultrasonic

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What is an Anemometer?

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An anemometer is a very commonly used instrument, especially in weather stations to calculate wind speed.

• The branch of science that deals with atmospheric forecasting is known as meteorology.
• It mainly involves the calculation of the speed of the wind.
• The device that is used to measure the speed of the wind is known as an anemometer.
• Anemos is a Greek word first coined by Leon Battista Alberti which means wind.
• Alberti used a mechanical anemometer which was placed perpendicular to the wind direction.
• Then the speed of the wind was determined by the angle of inclination of the disc.

Wind Anemometer

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How to make an Anemometer?

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The anemometer can be made using basic household materials.

• As compared to the modern anemometer, it will not give an accurate reading.
• But it gives an idea of how an anemometer works conceptually.
• A homemade anemometer can also be used to explain to middle school children the concept.
• These are simple to construct with a few basic materials.
• A few basic materials are needed to make the anemometer.
• It makes use of disposal cups to capture the wind, which causes it to spin.
• This type of anemometer is known as the Robinson Anemometer.

Materials Required 

• 4 paper cups
• 2 (non-flexible) straws
• A pencil with an eraser on it
• Tape
• Long pin
• Stapler
• A marker 
• A stopwatch

Procedure 

• Use the tape to put together the two straws in a cross position.
• At the outer ends of the straws, tape together and staple the cups making sure they are in the same direction.
• Take the pencil and the pin.
• It should be long enough to penetrate through the taped pipe at the center and into the eraser of the pencil on the other side in a T position.
• Mark one of the cups with the marker to make the counting of rotations in the wind with the help of a stopwatch.
• Now the anemometer is ready to be tested.
• Take the anemometer in the wind and note down its number of rotations.

Observations 

• This is a basic anemometer, it does not display the number of rotations.
• The readings have to be taken down manually.
• It can be done by watching the number of times when a marked cup completes its rounds.
• Keep the count for 30 seconds or 1 minute. 
• This anemometer can only give an idea of how fast the wind is blowing.
• To know the average wind speed, you can repeat the process once every day to find the average for a week.
• Also, you can do it multiple times a day to find out the average of a day.

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Types of Anemometer

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Anemometers are broadly classified into four types. These are:

1. Mechanical: Cup and Vane Anemometer
2. Non-Mechanical: Hot-Wire, Laser Doppler, and Ultrasonic
3. Pressure: Plate and Tube
4. Propeller

Different Types of Anemometer

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Mechanical Anemometer

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Mechanical anemometers are used to measure the speed of the wind with the help of a fan set attached to it. Different types of mechanical anemometers are

• Cup Anemometer
• Vane Anemometer

Cup Anemometer 

This type of anemometer has hemispherical cups.

• These cups (usually 3-4) are attached at the end of a horizontal rod.
• The horizontal rod is vertically attached at the center of a rotating wheel.
• It is the most simple form of an anemometer.
• It is one of the most commonly used types of anemometers

Cup Type Anemometer

Working 

This anemometer is attached to a rotating wheel, made of horizontal rods, which have cups at the end of them. 

• As the wind blows, the cups are forced to move, hence moving the wheel at the center.
• The faster the wind blows, the faster the rotation of the anemometer.
• The anemometer then calculates the number of rotations which is used to calculate the wind speed. 

Uses

• Meteorological Applications
• Educational institutions
• Researches
• Commercial Uses

Advantages

• Cheap
• Flexible Design
• Easy Installation
• Can be Operated Easily

Vane Anemometers 

The rotation made by the propeller-like blades is calculated by the anemometer.

• It can be called the smaller version of a windmill anemometer. 
• Windmill anemometers are used in larger fields for wind velocity and are not mobile.
• Whereas vane anemometers are mobile and easy to use. 

LCD Vane Anemometer

Working 

Its working is similar to the cup anemometer, only it has blades that rotate instead of cups.

• It is considered to be more accurate than the cup anemometers.
• The windmill is placed horizontally to the wind so that the blades rotate at a horizontal axis to the wind flow. 
• The number of spins per second is converted digitally to show the wind speed. 
• They are also referred to as propeller/ windmill anemometers. 

Uses

• Can be used for indoor and outdoor purposes.
• Also tells other parameters apart from the wind speed.

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Non-Mechanical Anemometer

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A non-mechanical anemometer is a device used to measure wind speed without using any moving parts. Different types of non-mechanical anemometers are

• Hot Wire Anemometer
• Laser Doppler Anemometer
• Sonic or Ultrasonic Anemometer
• Ping-Pong Ball Anemometer

Hot Wire Anemometer 

Works on the principle that air cools down a heated object when it flows over it.

Hot Wire Anemometer

Working 

• An electrically heated wire, which is thin, is placed in the wind.
• It uses the principle that a breeze cools down a hot object. 
• The faster the wind, the higher the temperature needed to keep it at a constant.
• Hence, the amount of power needed to cool down the wire is used to calculate the wind speed.
• It is useful in determining the direction and velocity of the wind by how quickly the wire cools down and how cool the temperature gets.

Uses

• In areas with relatively constant temperatures.
• Flow Hoods
• HVAC systems
• Exhaust monitoring 

Laser Doppler Anemometer

This type of anemometer works on the Doppler shift effect (change in frequency of a sound wave due to a reflector moving towards or away from an object). 

Laser Doppler Anemometer

Working 

• It uses a beam of light and is excellent at measuring even the slightest change in the wind flow. 
• It looks more like a machinery setup than a single device.
• The single light beam is further split into two. 
• When one of the beams is made to enter the anemometer, the amount of light that has been reflected off by moving air particles determines the velocity of the wind. 
• Laser beams do not disrupt the fluid’s path, also they do not need to be calibrated. 

Uses

• Used for high-tech applications
• Jet engines 
• River hydrology

Sonic or Ultrasonic Anemometer

Sonic or Ultrasonic Anemometers are expensive and very advanced.

Ultrasonic Anemometer

Working 

• Sound waves are sent between a pair of transducers, and the way their speed is affected is how the wind speed is calculated. 
• It has four sensors arranged in a square position.
• This anemometer can be either two-dimensional or three-dimensional and used for navigation and aviation purposes. 

Uses

• Aircrafts 
• Scientific wind turbines
• Automated weather stations 

Ping-Pong Ball Anemometer

These are made using a ping-pong ball. 

Ping-Pong Ball Anemometer

Working 

• A ping-pong ball is hung by a thread, as the wind blows horizontally it moves the ball.
• It (ping-pong ball) moves easily due to its lightweight nature. 
• Then, by measuring the angle of the string-ball apparatus and the vertical it achieves after being displaced by the wind, it determines the speed of the wind.

Uses

For an understanding of an anemometer at the middle school level.

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Pressure Anemometers

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Pressure anemometers are used to measure the pressure of the wind. Different types of pressure anemometers are

• Plate Anemometer
• Tube Anemometers
• Pitot Tube Anemometer

Plate Anemometer 

Its surface is used to measure wind pressure. 

Plate Anemometer

Working 

A spring balances the pressure of the wind on its face. Either a recorder or a gauge is used to determine the actual pressure of the wind by the compression of the string.

Uses

Used for high wind alarms on bridges. 

Tube Anemometers 

They are also called Windstock. It provides relative measurements of wind speed. 

Tube Anemometer

Working 

• A material is used to make a tube shape that is connected to wires. 
• The larger end of the tube is caught when the wind blows. 
• This determines the direction of the wind as the sock moves in that direction.
• The faster the wind blows, the tube rises higher and gives the readings. 

Pitot Tube Anemometer 

These are used for measuring the pressure of the and have a quick response. 

Pitot Tube Anemometer

Working 

• They are digital devices with a tube attached to them. 
• The tube is then inserted into a duct which converts the pressure into wind speed reading. 
• It utilizes a dual port system to measure flow using the differential pressure of the two ports.
• They can measure through a very high wind speed and velocity.
• They are mobile devices, have no rotating parts, and are easy to use.

Uses

• For pressure in air ducts
• Ventilating ducts/pipes

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Things to Remember 

• Meteorology is a branch of science that deals with the study of Weather predictions.
• Weather predictions can mainly be made by measuring the wind speed.
• An anemometer is an instrument/device used to measure the wind speed, wind velocity, direction of the wind, etc.
• The rotating anemometers calculate wind speed by counting the rotations per second. 
• Electrical anemometers use heat to measure wind speed, as a heated object will cool faster in a strong wind.
•  The electrical current required to keep the object at a constant temperature is a measure of the wind speed.
• Modern digital anemometers are more accurate and easy to use.

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Previous Year Questions

1. What is the power delivered to the particle that undergoes uniform acceleration. [NEET 2010]
2. Calculate the velocity of collision of the moving balls. [NEET 2010]
3. Calculate the ratio of linear momentum. [NEET 1993]
4. Calculate the impulse. [NEET 1989]
5. Calculate the work done to overcome the air ressistance. [NEET 1989]
6. Determine the second block’s speed after collision. [NEET 2015]
7. Determine the energy of the two particles. [NEET 2015]Calculate the factor of velocity loss by the ball.
8. Calculate the combined velocity of the moving body. [NEET 1996]
9. Calculate the work done by the force. [NEET 2016]
10. Calculate the distance of the particle for stable equilibrium. [NEET 2012]
11. Calculate the direction in which mass A moves after collision. [NEET 2012]
12. Determine the torque when the position vector is given. [NEET 2020]
13. Calculate the net work done by the vertical spring. [NEET 2007]
14. How much water a pump of 2kW can raise in a minute to a height of 10 m. [NEET 1990]
15. Calculate the factor of velocity loss by the ball. [NEET 1998]
16. Calculate the work done in the first 4 seconds by the particle. [NEET 1998]
17. Which of the following is true for a shell which explodes into parts. [NEET 1998]
18. Calculate the ratio of linear momentum. [NEET 1998]
19. Calculate the work done by the force in moving the object. [NEET 2005]
20. Calculate the ratio of kinetic energies for the ball. [NEET 2004]

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