How planes can significantly boost rainfall in their path

Planes flying over rain or snow can intensify the precipitation by as much as 10-fold.

A new study shows how planes can affect clouds, boosting rainfall up to 10 times in narrow bands.
A new study shows how planes can affect clouds, boosting rainfall up to 10 times in narrow bands. Image: Shutterstock

A new study by the American Geophysical Union, the airplanes, in addition to creating pollution, also mess with clouds as they pass through or over them. The study suggests that the planes could boost rainfall and snowfall by up to 10 times, and examined the microphysics behind it.

The rain- and snow-bursts are not caused by emissions from the aircraft but are the peculiar consequence of the aircrafts’ wings passing through clouds of supercooled water droplets in cloud layers above a layer of 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.

Dimitri Moisseev, a researcher at the University of Helsinki said, “The interesting thing about this feature is that it is caused by aircraft, but it is not caused by pollution. Even if there would be absolutely ecological airplanes, which don’t have any combustion, no fuel or anything, it would still happen.”

“Although the bands of enhanced precipitation are artificially created, the physical process jump-started by the passage of planes can occur naturally, which makes them useful laboratories for studying the formation of precipitation. Observing them may help meteorologists “nowcast” natural rain and snow conditions 2 to 6 hours into the future, which is essential for airport operations.”

“When you, like myself, look at the radar data every day there is always something interesting going on. Surprisingly enough, there are always new things that we cannot explain still.”

Moisseev found inquisitive streamers of increased precipitation in outputs from the campus radar antenna at the University of Helsinki Kumpula. The unnaturally straight fixes of exceptional precipitation showed up against a foundation of lighter rain or snow and appeared to twist toward the adjacent Helsinki-Vantaa airplane terminal.

Their shapes looked intriguingly like the opposite of cloud arrangements known as fallstreaks, hole punch or canal clouds, marvels which can happen when flying machine fly through billows of water droplets that are colder than 0 degrees Celsius (32 degrees Fahrenheit) — yet aren’t frigid.

In opposition to mainstream thinking, water can exist as a fluid well underneath the typical point of freezing– in any event, under explicit conditions. Water beads can take shape into ice all the more effectively if there’s a surface for it to hook onto, for example, dust particles. In mists with a couple of pollutions, water beads can remain fluid directly down to – 40° C (- 40° F).

That is, until a plane tags along and works things up. As the flying machine goes through a haze of these supercooled water droplets, changes noticeable all around weight can freeze the drops, which thus solidify others around them. As this chain response spreads out and the ice falls away, it can make the opening punch cloud arrangement.

The data in the new study suggests that the effect starts much higher up. Layers of supercooled water vapor float around the same altitude that planes approach the airport from, so when a plane passes through, ice crystals can fall from this layer into a lower cloud layer that is already raining or snowing. That feeds more ice into the cloud and boosts the precipitation along a narrow band behind the aircraft.

Moisseev said, “The interesting thing about this feature is that it is caused by aircraft, but it is not caused by pollution. Even if there would be absolutely ecological airplanes, which don’t have any combustion, no fuel or anything, it would still happen.”

The research was published in the Journal of Geophysical Research: Atmospheres.