Lidar (Light Detection and Ranging) is a remote sensing technology using laser beams to measure the wind speed and direction.
Based on pulsed Doppler heterodyne laser principle, the Lidar sends a light pulse at high frequency in the atmosphere and observe the signal backscattered by aerosols naturally present in the air.
The time between the pulse and the detection of the backscattered signal is processed by the system thanks to the Doppler effect and provides an accurate measure of the wind speed and direction. This measure is based on a physical constant of high accuracy: light speed.