This video shows how an anemometer measures air velocity. This anemometer is of analog meter which gives the total linear distance that the rotor moves during a prescribed amount of time. One needs to see the pointer movement and have to record the time. The division of linear movement of air and time gives the average velocity of air.
Watch the video. It shows how the velocity of air is measured by an analog anemometer.
How is manufacturer of this anemometer in video, thank you in advance