Scientists use laser tweezers to trap particles that trigger lightning strikes

Scientists at the Institute of Science and Technology Austria (ISTA) have developed a novel experiment using laser tweezers—focused laser beams known as optical tweezers—to trap and electrically charge single micron-sized aerosol particles that mimic ice crystals in thunderclouds. By precisely controlling these particles in a vibration-isolated lab environment, the team observed that the laser induces a “two-photon process” that ejects electrons from the particles, causing them to become positively charged over time. This setup allows long-term observation of the charging and spontaneous discharging behavior of individual particles, providing new insights into the microphysics of cloud electrification. The study aims to shed light on the longstanding mystery of how the first spark of lightning is initiated. Thunderstorm clouds accumulate charge through collisions between ice crystals and larger ice pellets, but the exact mechanism triggering lightning remains unclear. The ISTA experiment’s observation of spontaneous discharges in model ice crystals suggests a possible microscale process that could contribute to the buildup of electrical charge in clouds