More complex ultrasonic anemometers measure wind speed in three directions based on the time of flight of sonic pulses between pairs of transducers. However, the relative expense of the units is prohibitive for many ecological applications. Unlike mechanical anemometers, these devices have a rapid response time and the lack of moving parts allows them to be installed close to the ground or within vegetation, so they have the potential for measuring small-scale eddies and microclimatic effects. The second form of anemometers used in ecological studies are hot-wire anemometers, in which an electrically heated wire element is cooled by the wind, and the wind speed calculated by the rate of heat loss. Samson and Hunt, 2012) and may be appropriate for some microclimate applications. However, miniature propeller anemometers with integral dataloggers and the ability to measure temperature and humidity as well are now available at a relatively low cost (e.g. In part, this is due to the relatively large size of many units, making it difficult to measure within plant canopies or close to the ground, where the wind is decoupled from the background atmosphere. Handheld anemometers are frequently used by ecologists for short-term measurements, and they are less often installed with dataloggers to measure microclimate (see Table 2). While mechanical anemometers are still in use in meteorological stations, ultrasonic anemometers are becoming more popular. In the latter case, the device must either be held perpendicular to the direction of the wind or be mounted on a vane for automated measurements such devices typically measure direction as well as speed.

The cheapest and most widely used in ecological studies are cup or propeller anemometers, in which rotating cups or a propeller is driven by the wind. Gillingham, in Advances in Ecological Research, 2018 4.1.5 WindДЄnemometers, devices used to measure wind speed, generally fall into three categories. Before using an anemometer, it is important to determine how it should be positioned and what component of the total velocity its measurement represents.Isobel Bramer. Other wind speed meter, such as vane anemometers, are used with the tip aligned with the total velocity vector. If the cup anemometer is mounted with the shaft perpendicular to the horizontal, it will measure only the component of the wind that is parallel to the ground. The cup anemometer (used in weather stations) measures the air velocity in a plane perpendicular to the axis of its rotation cups. The term 'thermal anemometer' is often used to mean any anemometer that uses a relationship between heat transfer and velocity to determine velocity. The vane anemometer, thermal anemometer and cup anemometer (typically used in weather stations) are mostly used to measure the mean velocity, while the hot wire anemometers are usually used when turbulence characteristics are being measured, such as transverse measurements in a cross-section. They are less popular because their zero-flow reading is not stable, temperature and velocity response is slow, and temperature compensation is limited.ДЄn anemometer usually measures gas flows that are in turbulent flow conditions.

Temperature is simply proportional to flow rate. Anemometers are usually classified as constant-temperature, or constant-power anemometers.Д¬onstant-temperature anemometers are popular because of their high-frequency response, low electronic noise level, immunity from sensor burnout when airflow suddenly drops, compatibility with hotfilm sensors, and their applicability to liquid or gas flows.Д¬onstant-power anemometers do not have a feedback system. The four most popular anemometer models are: Vane Anemometers, Thermal Anemometers, Thermal Anemometers with Velocity / Temperature Profiling and Cup Anemometers. There is a wide range of anemometers models for directly measuring wind and air velocity. An anemometer can measure the total velocity magnitude, the velocity magnitude on a horizontal plane, or the velocity component in a particular direction.