![]() The fact that a stream of air will cool a heated object (the rate of cooling being determined by the speed of the airflow) is the principle underlying the hot-wire anemometer. ![]() This device is especially suited for the measurement of low airspeeds. In another type of wind-driven unit, revolving vanes operate a counter, the revolutions being timed by a stopwatch and converted to airspeed. A propeller may also be used to drive the electric generator, as in the propeller anemometer. The useful range of this device is approximately from 5 to 100 knots. The output of the generator operates an electric meter that is calibrated in wind speed. Most widely used for wind-speed measurements is the revolving-cup electric anemometer, in which the revolving cups drive an electric generator. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Īnemometer, device for measuring the speed of airflow in the atmosphere, in wind tunnels, and in other gas-flow applications.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives. ![]() Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Anemometers help engineers make these vehicles more aerodynamic. Laser anemometers calculate the wind speed around cars, airplanes, and spacecraft, for instance. Velocity is the measurement of the rate and direction of change in the position of an object. This type of anemometer is used in velocity experiments. Aerospace engineers and physicists often use laser anemometers. Wind speed helps indicate a change in weather patterns, such as an approaching storm, which is important for pilots, engineers, and climatologists. Uses of Anemometers Anemometers are used at almost all weather stations, from the frigid Arctic to warm equatorial regions. Other anemometers work by measuring the speed of sound waves or by shining laser beams on tiny particles in the wind and measuring their effect. By comparing the air pressure inside the tube to the air pressure outside the tube, wind speed can be calculated. A tube anemometer measures the air pressure inside a glass tube that is closed at one end. (Air pressure itself is measured by an instrument called a barometer.) A tube anemometer uses air pressure to determine the wind pressure, or speed. Wind speed can also be determined by measuring air pressure. The higher the wind speed, the more power is required to keep the wire at a constant temperature. The amount of power needed to keep the wire hot is used to calculate the wind speed. (That is why a breeze feels refreshing on a hot day.) In a hot-wire anemometer, an electrically heated, thin wire is placed in the wind. A hot-wire anemometer takes advantage of the fact that air cools a heated object when it flows over it. Other anemometers calculate wind speed in different ways. The rod of windmill anemometers rotates horizontally. A similar type of anemometer counts the revolutions made by windmill-style blades. Because wind speeds are not consistent-there are gusts and lulls-wind speed is usually averaged over a short period of time. The anemometer counts the number of rotations, or turns, which is used to calculate wind speed. The stronger the wind blows, the faster the rod spins. As the wind blows, the cups rotate, making the rod spin. The most common type of anemometer has three or four cups attached to horizontal arms. They are also important to the work of physicists, who study the way air moves. Anemometers are important tools for meteorologists, who study weather patterns. An anemometer is an instrument that measures wind speed and wind pressure.
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