The extra rain and snow aren’t caused by the aircraft’s emissions, according to the research.
Rather, it’s a unique consequence of an aircraft’s wings passing through clouds of supercooled water droplets in cloud layers above active rain or snow
Under the right conditions, this effect can boost rain and snow storms over airports, where many planes intersect the cloud layer on approach and descent.
“The interesting thing about this feature is that it is caused by aircraft, but it is not caused by pollution,” said Dimitri Moisseev, a researcher at the University of Helsinki and the Finnish Meteorological Institute and the lead author of the new study in AGU’s Journal of Geophysical Research: Atmospheres. “Even if there would be absolutely ecological airplanes, which don’t have any combustion, no fuel or anything, it would still happen.”
Meteorologists have known that passing aircraft can freeze water droplets into ice crystals and previous work had suggested that the process could enhance rain and snow in underlying clouds, but the effect had not been captured in detail until now.