Planes punch huge holes in clouds

摘要

Giant holes in clouds are created by aircraft. For the first time, a computer model has shown how these holes can grow to be tens of kilometres across in a few hours. The holes form because the clouds are supercooled, meaning their water is liquid despite being below o °C. Any disturbance to this state - a plane for instance - turns the water into ice crystals that fall away, leaving a small hole. Andy Heymsfield of the National Center for Atmospheric Research in Boulder, Colorado has used a simulation to show why they then grow so big.