Aeolus satellite: Tracking the world's winds from space
The Aeolus satellite carries a pioneering instrument, Aladin, which uses laser light scattering and the Doppler effect to collect wind data. On their website, ESA explains how Aladin works: "The laser generates high-energy UV light, which is beamed towards Earth through a telescope. As the light travels down through the atmosphere, it bounces off molecules of gas, particles of dust and droplets of water. This scatters some of the light in all directions, including back to the satellite where it is recorded by Aladin. By comparing the shift in frequency of the received light from the transmitted light caused by the Doppler effect, the motion of the molecules in the atmosphere can be measured, revealing wind velocity."