What is an anemometer?

Have you ever heard of Leon Battista Alberti? Perhaps not. However, it was him who, in the XXth century, invented the principle of the anemometer. And do you know what an anemometer is? It is a device for measuring wind speed (or pressure)! Measuring temperature and humidity is good… but measuring wind speed is also very important in weather forecasting. So what is this device?

Why measure wind speed with an anemometer?

Of course, wind speed is an important piece of information in weather forecasting, as is the measurement of temperature, for example. But why is that? The anemometer is a valuable piece of meteorological equipment for one simple reason: the wind is an essential parameter for predicting and understanding changes in weather conditions. You may have already heard that the tide has turned, and therefore the weather will change. There is some truth in this!
Of course, the anemometer is not only used by the weather service. Are they the only ones to measure temperature or humidity? No, of course not! Other sectors such as air transport or shipping, which are very prone to bad weather and sudden changes in the weather, are also major users. In construction or industry, measuring wind speed is also important.

Beware, however: contrary to what you might think, anemometers do not measure the direction of the wind. They only estimate the speed and pressure. To obtain its direction, you need to combine the anemometer with a wind vane!

The %s() can be combined with the Netatmo Smart Anemometer to keep you informed of the wind speed and direction from your home in real time! This connected anemometer measures the wind speed and direction but also alerts you in case of strong wind: don't take any risk.

How does the anemometer measure wind speed?

Let's take the example of a classic cup anemometer. Most often, the device must be placed on a 10-metre high mast (difficult to have one at home…). The device consists of three small cups that are installed on horizontal arms separated by regular spaces.

And then the wind starts to blow: the anemometer starts to rotate which allows the wind speed to be measured according to the number of rotations made per second. The principle is elementary and is based on the laws of aerodynamics, which impose a greater resistance to hollows than to curved surfaces.
In fact, this is how one type of anemometer works. The principle is different for each model! But each time, the data is the same (pretty much).

The evolution of anemometers since the 15th century

The first anemometer mentioned in the introduction, designed by Leon Battista Alberti in the 15th century, was a plate anemometer (more on this type of anemometer later). On this device, the wind force was then estimated by taking into account the angle of the mobile plate rotating around a horizontal axis with respect to the vertical. This plate was placed in the balance between the force of the wind and the power of gravity.

Over the centuries, inventors have evolved the concept and nature of anemometers. Other parameters were then used to measure the speed and pressure of the wind: the evolution of the frequency by the Doppler effect between a beam emitted in the direction of the wind and its return, the variation of the pressure in a tube, the time is taken for a sound emitted to be received by a receiver… it doesn't matter what the means are, in the end, only the accuracy of the measurement counts!

Combine wind speed measurement with temperature, humidity, moon phase and all your weather information thanks to the Netatmo Smart Weather Station and the Netatmo Smart Anemometer . Take advantage of it to anticipate at the same time your outdoor activities, the weather and the indoor air quality of your home! Do not miss out on good weather or sunshine!

The different types of anemometers

Today, there is not one anemometer, but many. Although their nature changes, their function remains the same: to measure wind speed and pressure secondarily, or vice versa. None of them give the direction of the wind without a weather-vane.

Anemometers measuring wind speed

First, let's take the cup anemometer (Robinson's). A commonly used cup anemometer or Robinson’s anemometer measures horizontal wind speed and withstands extreme conditions.
Among the instruments that also measure wind speed, the main ones are the propeller anemometer (easily used by home users), the windmill (or Byram) anemometer, the hot-wire anemometer, the ultrasonic anemometer, the bi-directional anemometer, the acoustic resonance anemometer, and the laser anemometer. To measure wind speed and not as a weather forecast.

Wind pressure anemometers

Anemometers that are more specialised in measuring wind pressure operate differently by design. Some of these weather instruments are based on measuring the force that the wind exerts on a plate that is held facing it, but others measure the wind pressure through a U-tube with a built-in pressure gauge.
These devices for analysing wind pressure are less used than those for providing information on wind speed, but they are still used.
Among the anemometers designed specifically to measure wind pressure but also capable of providing wind speed, we can mention the very first anemometer: the plate anemometer. It has evolved but its operating principle has remained the same.

Other anemometers of this type are ball, tube, and Pitot tube anemometers.
In the end, it does not matter how the anemometer works. What matters is the accuracy of the wind data it provides! Do you know how your thermometer to measure temperature works? Not sure, and in fact, not so important.
If you want to buy an anemometer and do your wind speed or pressure measurements, consider your measurement needs and the prices of the instruments on offer. Choose the ideal product according to your criteria.
In short, the anemometer is the reference device for measuring wind speed and pressure. Some types can be purchased and used at an affordable price, but others are best left to professionals (such as weather forecasters).