MONITORING STATION INSTRUMENTATION AND MEASUREMENTS - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 42

4.1.3 Air Temperature
Air temperature is an important characteristic of a wind farm's operating environment.
It is normally measured 2-3 m above ground level or near hub height, or at both levels.
In most locations, the average air temperature near ground level is within 1 ◦ Cofthe
average at hub height. Air temperature is used to estimate air density, which affects
the calculation of power production. The air temperature readings are also utilized in
the data validation process to detect icing.
An ambient air temperature sensor is typically composed of three parts: the trans-
ducer, an interface device, and a radiation shield (Fig. 4-5). The transducer contains
a material (usually nickel or platinum) exhibiting a known relationship between
resistance and temperature. Thermistors, resistance thermal detectors, and temperature-
sensitive semiconductors are common element types. The resistance value is measured
by the data logger (or other interface device), which then calculates the air tempera-
ture based on the known relationship. The temperature transducer is housed within a
radiation shield to prevent it from being warmed by direct sunlight.
Figure 4-5. A temperature sensor. Source: Campbell Scientific.