Laser Used to Create Clouds in European Laboratory

Swiss researchers have successfully used laser pulses to create small clouds in the laboratory, a technology they say could possibly be used to create rain on demand. After firing short pulses of infrared laser light into a chamber filled with water-saturated air at -24 degrees C, scientists observed linear clouds in the laser’s wake — similar to the jet contrails created by airplanes. In addition, they found the volume of condensed water droplets inside the chamber increased by half. Jérôme Kasparian, a researcher at the University of Geneva, Switzerland and lead author of the paper published in the journal Nature Photonics, said the laser stripped electrons from the atoms within the air, encouraging formation of hydroxyl radicals, which convert sulphur and nitrogen dioxides into particles that essentially act as seeds to grow droplets of water. After sending similar bursts about 60 meters into the sky over Berlin, the scientists observed no visible changes, but say they were able to confirm that the density and size of water droplets spiked. “As in the lab, the effect is clearly detected,” Kasparian said. But one critic noted the creation of clouds in the laboratory required conditions of extremely high humidity at very low temperatures, conditions rarely found in nature.