When conditions are right, a jet or turboprop airplane traveling through a cloud can cause it to snow, according to a study in this month’s Bulletin of the American Meteorological Society. Airplanes that penetrate altocumulus clouds containing supercooled droplets of water can cause some of the moisture to freeze and fall to the ground, leaving holes or channels in the clouds. “Just by flying an airplane through these clouds, you could produce as much precipitation as with seeding materials along the same path in the cloud,” said Andrew Heymsfield, a scientist with the National Center for Atmospheric Research (NCAR) and lead author of the study. As air is forced over the wings or the tips of propellers, its temperature falls, causing the droplets to form. The Pacific Northwest and western Europe often experience weather systems that are susceptible to this kind of event.
“This apparently happens frequently, embedded in the cloud layers,” Heymsfield told Science Daily. “You wouldn’t necessarily see it from a satellite or from the ground.” Heymsfield said he had no idea this was occurring, but just happened to be flying in a research aircraft and observed the formation of a hole and a burst of snow. “This data set just fell in our laps. It was a lucky break,” he said. The effect is not common enough to have significant climactic impact, Heymsfield said.
