In Search of Contrails

Early in my career my work group formed a baseball team. We played weekly against other departments in our office. Our team was called Blue Sky Batters. A double-entendre; an allusion to hitting the ball high and (it was hoped) far, and the nature of our research-oriented work.

Skies Above Windy Hill Park, Thornhill, Ontario
Skies Above Windy Hill Park, Thornhill, Ontario

Blue skies have been in the news recently. As reported by the Max Planck Society, published in Physics.org , “Air pollution has dropped by 20 to 40 percent, and daily emissions from aircraft have decreased by up to 85 percent. This means that the atmosphere is much less polluted with emissions from transport and industry.”

As the argument goes, the pandemic-inspired lockdown has reduced the operation of all sorts of polluting machines, notably airplanes. From this, it follows that less air traffic results in fewer condensation trails to cloud the skies, and blanch the blue. I am not in a position to verify the claims as I cannot really tell whether the blue sky I saw today is more or less blue than the same sky of a few months ago. In fact, to be fair, I would probably have to compare today’s with one from about a year ago that might share similar weather conditions (such as humidity). My blue-sky-memory-comparison ability is not that good. I walked over to the park, next door to our house, and looked up into the sky. A quick scan revealed a mostly blue sky, which did seem dark, but I can’t say whether it was darker, but clearly it had no condensation trails.

However, these claims do match my own experience. First, I have noticed I am sniffling less. I attribute this to less air pollution. Second, there are very few planes flying over head, unlike many of the pre-coronavirus-days, when there might be one every few minutes.

News reports state that airlines have reduced their number of flights by between 85-95%. Looking at Flightradar24 doesn’t confirm that percent reduction, but it is certainly clear that there are not many planes in the air.

Map showing flights over South-Western Ontario.
Map showing flights over South-Western Ontario.

Over the next few weeks, a team of German Scientists will measure pollutants over European urban areas and the flight corridor to North America. “The aim of these research missions is to investigate how reduced emissions from industry and transport are changing atmospheric chemistry and physics.“ [1] All this work will be completed as part of the Bluesky research programme.

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