Anemometer: Types, Uses and It’s Working Principle
When you think of “weather,” wind is often one of the first things that comes to mind. Though it can cause catastrophic damage, wind is also a cherished part of our daily lives. Understanding the wind speed and direction—whether for personal safety or planning activities—is valuable information. Unlike a sprinter or a race car, you can’t easily measure wind speed with a stopwatch. Thankfully, scientists have developed ingenious devices called anemometers to measure wind speed accurately. Let’s take a closer look at how they work.
What is an Anemometer?
An anemometer is an instrument used to measure wind speed, intensity, and direction. It’s also capable of measuring wind pressure. One popular example is the Fluke 925 Vane Anemometer. A typical anemometer consists of three to four cups attached to horizontal arms, which are connected to a vertical rod. As the wind blows, the cups rotate, causing the rod to spin. The faster the rod spins, the stronger the wind. Anemometers are used in various applications, such as measuring wind conditions before sailing or assessing the airflow during HVAC installations.
In today’s digital age, we’ve seen significant advancements in electronic devices. We now have a wide range of instruments to measure climate change, temperature fluctuations, and wind speed. Below are some examples of different types of anemometers used in various settings.
Mechanical Anemometer
A mechanical anemometer uses small propellers, akin to miniature wind turbines, to power its generator. As the wind blows, it spins the fan blades, which in turn drive a small generator, similar to a bicycle dynamo. This generator is connected to an electronic circuit that provides real-time data on wind speed.
Ultrasonic Anemometer
An ultrasonic anemometer features two or three pairs of transducers arranged at right angles to each other. Each transducer emits high-frequency sound waves to its counterpart. The time it takes for these sound waves to travel between transducers is affected by the wind. By analyzing these time variations, the device can calculate wind speed and direction.
Doppler Laser Anemometer
A Doppler laser anemometer emits one or more electromagnetic laser beams into the air, which then reflect off particles like dust or water droplets. As these particles move with the wind, the frequency of the reflected laser beam changes—a phenomenon known as the Doppler shift. By measuring this frequency change, the anemometer can precisely determine wind speed.
Hot-Wire Anemometer
A hot-wire anemometer uses an electrically heated wire, much like the filament in an old light bulb. As wind blows over the wire, it cools down, changing the wire’s electrical resistance. This change can be measured to calculate the wind speed. Hot-wire anemometers are particularly effective for measuring turbulent airflow and are commonly used in industrial applications, such as monitoring fluid flow in aircraft engines
An ideal anemometer can measure wind speed with an accuracy of up to 0.5 m/s (2 km/h or 1 mph), which is often more precise than necessary for many applications. However, keep in mind that wind speed is variable and constantly changing, so any reading will give you a rough estimate of how fast the air is moving. Interested in buying an anemometer? Explore the Fluke 925 Vane Anemometer here.