Wind direction

A wind direction indicator, also known as a wind vane, weather vane, or, more specifically, an anemoscope, is an indicating instrument for determining wind direction. It relies on a movable measuring element that aligns itself with the dynamic pressure of the wind.

A wind direction indicator can be considered a static system with only one mechanically stable equilibrium state. The input element is the vane surface, which is arranged asymmetrically to the axis of rotation and on which the wind exerts a torque if it is not aligned parallel to the wind direction. The output element is the wind direction indicator itself, since its orientation corresponds to the wind direction (see also directional stability).