The possible mechanism behind laser-induced water droplet formation is reported in Nature Communications this week. This technique builds on previous work to provide an alternative scheme to trigger condensation in the atmosphere and could allow for applications of lasers in the atmosphere, including remote sounding or laser-based control of rain.

Long-standing schemes to seed clouds involve dispersing small particles in the air to initiate the growth of water droplets. Intense laser beams ionise air and are thus expected to play a role in assisting condensation. Jerome Kasparian and colleagues perform measurements on laser-induced condensation over the Rhone River in Geneva under different atmospheric conditions. They find that the laser triggers the growth of micrometer-sized water droplets when humidity exceeds 70%.