Lidar

Calipso's Lidar (Light Detection And Ranging) is a laser operating as a radar. From the satellite, it sends a laser beam towards the Earth, which is dispersed by the molecules and particles in suspension in the air. The part of the incident light reflected by the clouds and aerosols is captured by a telescope fitted with a photoelectric sensor, which sends its information to a computer at each time step. Thus, Lidar determines the composition of the atmosphere depending on the altitude, and it does so with unequalled precision.