An Anemometer is the most common weather station instrument. The weather station staff use this revolutionary object to determine the air speed. However, the Anemometer is capable of finding out the wind direction just like a wind vane.
Now, if you are wondering how to measure wind speeds with an Anemometer, you should keep your calm and read the entire article; it will take a maximum of 5 minutes.
The wind speed varies every second. So, the final wind speed is always the average of the Anemometer readings over a short amount of time.
The Revolutionary Anemometer device was invented in the 15th century, and it went through a number of design-related changes over the years. These days, there are different types of Anemometers in the market.
Most people use the mechanical one and Hotwire one. But, a Laser interferometer anemometer is also popular. More or less, the working mechanism is similar for all these anemometers.
So, let’s know how these instruments work.
What Does an Anemometer Work
In simple words, Anemometer is a horizontal windmill-like instrument used to determine the direction and speed of any current of gas.
One can calculate wind pressure along with the wind quality with the help of an Anemometer. A popular architect named L. B. Alberti designed the very first Anemometer, and it is used by meteorologists to study the weather pattern.
Apart from climatologists, pilots, physicists, engineers also need to know how to measure wind speeds with an Anemometer. After all, wind speed is directly related to weather patterns.
An Anemometer can tell whether any storm is approaching a particular location or not.
Starting from the tropical equatorial region to the snowy Arctic region, the Anemometer gives accurate results everywhere. An Anemometer has 4 horizontal shafts, and a cup-shaped piece is attached to the end of every shaft.
These four horizontal arms of Anemometer are attached to a vertical rod.
Whenever the concave side of the cup-shaped pieces catches wind, the horizontal shafts start to rotate. As the wind becomes stronger, the Anemometer spins faster.
From this spinning, you can calculate the wind speed in the unit of rpm or rotation per minute. Anemometer generally counts turns digitally for around 30 seconds and finally shows the wind speed in rpm.
How to Measure Wind Speeds with an Anemometer
Do you know that wind speed can also be derived from the data of air pressure?
There is a glass tube inside the Anemometer for air pressure measurement, and it is closed in one end. Besides, the wind speed can also be determined from the velocity of the sound wave.
Traditional Anemometers used to use a number of such methods to calculate the final wind speed.
These days, people are using digital anemometers, and they provide accurate readings instantly. As mechanical or digital anemometers are mostly used everywhere, we will talk about it first.
If you want to know how to measure wind speeds with an Anemometer, you should read the following steps.
Step 1: Instruction Manual
For a handheld Anemometer, you will get an instruction manual created by the manufacturers. So, this instruction manual will contain a number of diagrams and feature-related details of the Anemometer.
Users need to go through all of these before they start setting up their own Anemometer.
Step 2: Input the batteries
After installation, it is time to focus on selecting the battery for your Anemometer. Like set-up instructions, the instruction manual also contains which type of battery should be used in your Anemometer.
To add the batteries for your Anemometer, you will have to unscrew the back of the Anemometer and place those batteries. Don’t forget to screw it back before you start using the device. Now, it is time to press the on/off button of the Anemometer.
Step 3: Decide on the units of measurement
Anemometer is capable of showing the users the wind speed in multiple units of measurements. These are km/hour, ft/ minute, fit/ second, knots and m/ hour.
But, you can choose your preferred unit of measurement through some adjustments.
Step 4: Position the Anemometer accurately
Now that you are ready to measure the wind speed with the help of your Anemometer, you should position the device in the windiest place of your home.
For better results, come outside with your Anemometer and place it in the direction of the wind. For an accurate reading, you can go to an open space like a park with your Anemometer as well.
Make sure there is not an object which blocks the wind from touching the cup-shaped pieces of the Anemometer. If possible, hold your handheld Anemometer on top of your head to prevent obstructions.
Step 5: Take more than one readings
The wind can be categorized into multiple forms depending on the speed of the air. These forms are light air, gentle breeze, fresh gale, storm, gust, hurricane, etc.
So, the anemometer reading will fluctuate every minute.
That is why, to know the actual reading, you will have to count on the average of wind speeds reading. Collect the Anemometer reading 4 to 5 times at a regular interval of 5 to 10 minutes.
Now, let’s learn how you can measure wind speeds with the help of other types of Anemometers.
Sound waves need a medium to travel, and it definitely impacts the movement of air molecules. So, the ultrasonic Anemometer uses sound transmitters, receivers, etc.
Ultrasonic Anemometer uses high-frequency sound waves and shows the final wind speed on the small LCD screen.
In the case of a Laser Interferometer Anemometer, you use a laser beam instead of the sound wave. Other than this, there is also Hot-Wire Anemometer. Hot-wire Anemometer works just like wind chill.
In the case of hot-wire Anemometer, you will just have to place it in a windy place. The wind will come and will pass through the hot electric circuit.
Finally, you will get to see the wind speed reading. For turbulent airflow mainly this type of Anemometer is used.
Fastest Wind Speed Ever Recorded!
Wind keeps blowing from high-pressure zone to low-pressure zone to balance out the air pressure in the atmosphere. So, the air pressure fluctuation between two places is directly proportional to the wind speed.
Other than air pressure, seasonal temperature change, the centripetal acceleration, and Earth’s rotation on its axis can also be contributing factors for wind speed fluctuation.
Some windiest places on the Earth are Antarctica, Dodge City of Kansas, Baku in Azerbaijan, Newfoundland, Scotland, Oklahoma, etc. In Antarctica, the Katabatic wind can show speeds up to 168 miles per hour.
The Canadian city of Saint John’s experiences an average wind speed of 50 miles per hour throughout the year.
There is a city named Tornado Alley in Oklahoma where the wind speed reached 300 miles per hour and 286 miles per hour during the tornado of 1999 and 1991, respectively.
So far, the fastest wind speed ever recorded on Earth by an Anemometer (except tornado) is 253 miles per hour, and it was recorded on 10th April 1996 at Barrow Island of Australia.
But, the wind speed was so high because of the tropical cyclone of Olivia on the coast of Australia. Earlier to this, for nearly 62 years, the fastest wind speed recorded by an Anemometer was 231 miles per hour, and it was recorded in Mount Washington in the year 1934.
There was an observatory in the Mount Washington Auto Road Stage Office which recorded this wind speed around 90 years ago with the help of an Anemometer.
How Does a Hot Wire Anemometer Work
Hot Wire Anemometer is a special instrument used for determining the velocity of the fluid. Hot Wire Anemometer features a thin wire which gets heated up electrically.
Now, if you calculate the amount of wire heat loss, it will be easier for you to determine the final speed. First, let’s see how the Hot Wire Anemometer works.
Basic working principle of Hot Wire Anemometer
When an electrically heated up wire is placed in the middle of a gaseous stream, a heat transfer takes place. Due to this, the wire temperature is reduced.
Heat transfer results in variation in wire resistance, and it helps in calculating the flow rate easily.
Constant current method
In this case of a Hot Wire Anemometer, a constant current is sent through the wires. Now, when the gas flow starts, a heat transfer takes place to the flowing gas, and it decreases the temperature of the actual wire.
In this case, a galvanometer is used to measure the resistance fluctuation and the speed of the gas.
Constant temperature method
In this process of the constant temperature method, you will have to keep the resistance and the temperature of the sensing wire to a constant.
Here, an electrical current needs to pass through the wire to bring back the temperature to its initial condition. The constant temperature method of the Hot Wire Anemometer is pretty popular these days.
How to Determine Wind Direction
Anemometer is more like a wind vane, and whenever the air touches it, the device starts rotating. Anemometer has four horizontal arms attached to a vertical rod to balance the weight.
So, the arrow-shaped arm points the direction of the wind when the spinning stops. Apart from a wind vane, a windsock is also used to find out the direction of the wind. Let’s know in detail how one can determine the wind direction.
Step 1: Feel the wind
First, you will have to feel the wind with the help of your skin and other sensory organs. One can observe the clouds in the sky and note in which direction they are floating.
The gust of wind makes the big trees move, and so, it is easy to learn the wind direction at that time. One can also try listening to the wind flow past them.
Step 2: Watching waters
Do you know that the ripples always flow in the direction of the wind? One can drop a paper boat or an empty bucket on a water body to determine the direction of the wind. But, this method doesn’t show the most accurate result.
Step 3: Choose an obstruction-free space
From the first two techniques, you may have got a vague idea about the direction of the wind. To find out the most accurate direction degree-wise, you should use a mechanical anemometer.
But for this, you need to place the Anemometer in an open space where there is no obstruction for the wind. If possible, hold the Anemometer as high as possible over your head.
Step 4: Using the Anemometer
Once you find an open space for your Anemometer, you need to keep it steady and take the Anemometer reading for a number of times. The users should take the readings after an interval of 30 seconds at least.
Not all the readings will show the accurate degrees for the wind direction, but with 4 to 5 readings, you will be able to decide the degree.
Step 5: Using other wind devices
If you don’t own a digital Anemometer, you can make your own Anemometer with the help of a rod and some cups. The spinning cups help the users know the air direction.
The user can use a windsock as well. When the wind blows through the sock, the sock points in the direction of the wind. Wind Vane also points at the direction of the wind with the help of its arrow-like arm.
If you follow these steps one by one, it will be pretty easy for you to determine the direction of the wind.
FAQs about How to Measure Wind Speeds
What is an instrument commonly used to measure wind speed?
Well, the wind speed is measured with the help of an Anemometer. Anemometer is also used for measuring air pressure.
Though there are various types of Anemometers available in the market, we suggest using a mechanical Anemometer or Hot Wire Anemometer for the most accurate result. The user can even make his or her very own Anemometer at home with the help of cups, rods, glue, etc.
How to measure wind speed without an anemometer?
Other than Anemometer, there are other devices that can calculate the wind speed. These devices are Doppler Radar, Laser-based LIDAR, Sound-based SODAR, etc.
If you have none of these devices, you can use a simple ribbon and stick to find out the wind speed. First, align the ribbons and tightly fasten the end of those ribbons together.
Now, glue the ribbons to the stick and hold it high to measure the wind speed with the same method as your homemade Anemometer.
What is the function of Anemometer?
Well, it can show the users the result of wind speed, air pressure, and the direction. One will have to count the turns of the spinning Anemometer in the presence of the wind to find out the speed in RPM.
Anemometer even has a glass tube for calculating the air pressure.
What is the symbol for wind speed?
To represent calm wind, there will be a small open circle, and it generally indicates wind speed being less than 2 miles per hour. There can be other feather-like symbols.
When there is a single line and a black solid triangle attached to it, the wind speed would be 55 to 60 miles per hour. There can be feather-like symbols with a black triangle on the end as well.
When the wind speed is between 119 and 123 miles per hour, you will see a single horizontal line with one feather-like line and two solid black triangles.
How fast is a wind knot in mph?
Knot is nothing but the speed unit representing 1 nautical mile per hour, and it is around 1.15 miles per hour. Wind speed can be calculated in both miles per hour and knots.
What are the 4 types of wind?
There are Planetary wind, local wind, trade wind, periodic wind, etc. However, the local wind can be categorized into four different types such as hot wind, cold wind, slope wind and convectional wind.
Other than these, there are still Easterlies, Westerlies, doldrums, and so on.
What is the normal speed of wind?
Well, the normal speed of wind is somewhere between 6 mph and 10 mph. Of course, the normal wind speed will be more for windy cities like Chicago, Scotland, Kansas, etc.
Wind with a speed less than 10 mph is often considered as a light breeze. For windy cities, the normal wind speed is around 15 miles per hour.
How do you calculate wind speed from wind?
One will just have to take Anemometer outside and mark a cup with red color. Now note down how many times the red cup is reaching the same point in 30 seconds and finally multiply the number of turns by 2.
By this process, you will give you the result of wind speed in rotation per minute.
In a nutshell, the Anemometers are not that expensive. So, if you are aspiring to become a climatologist, pilot, or aeronautic engineer, you should think about buying an Anemometer for your own small projects.
To make an apparatus like Anemometer at home can be of great fun. All you will be needing are four cup-shaped pieces along with wooden rulers, nails, tape, hammer, stopwatch, and a large dowel rod.
The base of the device should be square-shaped, and the spinning arms should remain horizontally. Home-made handheld Anemometer will give you accurate wind speed as well.
In the coming years, people might come up with a more flexible and small model of Anemometer device, but the basic working principle will remain the same.