A wind vane
is an instrument used to determine the direction of the wind. It is generally installed on a pole about 10 meters high in the open space around it.
Under the action of wind pressure, the weathervane arrow points to the direction of the wind. A weather vane is basically an asymmetrically shaped object with its center of gravity fixed on a vertical axis.
When the wind blows, the end that creates greater resistance to air flow will rotate with the wind, indicating the wind direction. The arrow of a weathervane always points to the source of the wind.
The shape of the wind vane can be divided into four parts: tail, balance weight, pointing rod, and rotation axis. Wind speed and direction are measured using magnetic wind speed cups and wind vanes respectively. The magnetic wind speed cup usually has three symmetrical wind cups, which are fixed on the vertical axis so that the diameter surface of each wind cup is vertical.