Contrails are human-made clouds. They form in air above about 25, feet, when that air is moist and colder than degrees Celsius. Like regular clouds, they arise when water vapor, in this case from the engine exhausts, forms into droplets by condensing onto particles in the air, in this case soot from the engines.
Within a second, the water droplets freeze to make tiny ice crystals that show up visually as contrails. If the air is not cool or moist enough, contrails may not form or may disappear quickly. But at other times, they stick around — either as tight, white lines in the sky, like chalk marks, or gradually spreading to create thin layers of ice clouds. They are similar to natural cirrus clouds and are often called contrail cirrus clouds. In areas with high amounts of air traffic, they can merge to cover as much as 38, square miles, roughly the size of Indiana, and last for many hours or even days.
The concern is not new. But understanding of the role of contrail cirrus clouds to climate is growing. An infrared satellite image showing dozens of contrails over the southeastern United States during a single morning in January Like regular cirrus clouds, contrail cirrus clouds have two competing effects on climate.
They shade us by reflecting incoming sunlight back into space. During the day, cooling compensates part of the warming. But at night, with no sunlight, only the warming effect operates.
Red-eye flights are a red light for climate. Research in the American South and Midwest has concluded that when contrails are around, they raise night-time temperatures sufficiently to reduce the day-night differences by 3 degrees C. So how does this play out globally? What does it mean for climate change? The figure is for , the base year for the U. Do new technologies make flying sustainable?
Choose individual airlines carefully Some airlines are taking voluntary steps to reduce carbon pollution. Climate aviation facts One return flight from Montreal to London emits as much carbon emissions as heating a European home for an entire year. If the aviation sector were a nation, it would be among the top 10 global emitters.
It is responsible for 12 per cent of transportation emissions. The global tourism industry is responsible for eight per cent of global emissions — more than the construction industry! Airline flying is going up five per cent a year but efficiency improvements have only increased by one to two per cent.
Airline emissions make up a little more than three per cent of total emissions in Canada. The total carbon impact of a single flight is so high that avoiding just one trip can be equivalent to going gasoline car-free for a year.
Tom Green, climate policy analyst. Take some steps Fly only when necessary and stay longer. Make a small change If you must travel, offsets are a partial solution to lowering your impact. Five ways to reduce your carbon footprint. Here are some meaningful decisions you can make to reduce your carbon footprint when you fly. Wonder Words airplane track sky trail trace streak artificial fume dense exhaust vapor contrail condensation evaporate canvas navigation smoke fade Take the Wonder Word Challenge.
Join the Discussion. Lilly Feb 19, So, why the same airplane can stop doing it from one moment to another in same weather conditions? Feb 20, Hey, Lilly! It's now or never. Jan 15, Sep 25, We're glad you enjoyed the video, tom! Thanks for being our Wonder Friend! John Jun 21, I am just curious. I remember back when I was a kid I am now 36 that when the high flying planes left their contrails they would fade shortly after.
Why has this changed over the last 10 years or so? There is now a white haze that lingers and spreads out behind many of these planes. What is your theory about this? Do you have any information that can enlighten us?
Maybe some references to follow up on? Appreciate any info you can provide. Jun 28, Jake smith Feb 23, Seriously , look up former Ex government employee Kristen Meghan.
She is a Geo engineering whistle-blower. There are plenty of smarter people than you and I that understand what's going on. Make sure you know the facts before you have google put mis information about this subject on the web for children. Shame on you guys. And just so you know, all commercial air liners planes don't make fake smoke.
Feb 23, Thanks for being so respectful, Jake! Kiki Jan 8, Jan 9, Tess Feb 21, You are liars of the worst kind. These are not contrails, this is weather modification, geo engineering program. How dare you make light of it as kids are breathing it and dying. You are murdering people for the govt. You stink. Feb 22, Yogesh Oct 29, I didn't know about this white tracks like why these plains are leaving this type of track N then I searched on Google N Wonderopolis you rally helped me in this topic Oct 31, You're very welcome, Yogesh!
Dakota Jun 19, Jun 20, And if you were to say like some that was 2 lines would it go away before you finish. Nancy Jun 19, This is really cool the way they write massages in the air with a plane. Hi, Nancy! We appreciate your comment! B Jun 19, I have never seen it be done before but it looks pretty. The work they do is awesome. Teiona M. Jun 19, I liked that you guys told us about why air planes leave trails.
Also how they leave letters with the air planes. Monet Gray Jun 19, I liked how you can write words in the sky with the planes. I also like when you make shapes that's really pretty.
Once i went to a air show and it had people sky writing and it was really cool. I would love if someone did that to me. That sounds like a lot of fun, Monet Gray! We bet you learned a lot! Anya A. Thats cool how people can purpose by skywriting. I didnt know that skywritting was way back to I saw a air show before its really cool. Cole H Jun 19, I didnt know that the "special smoke" was made from the exhaust overheating and oil being sprayed on it. Pretty odd. Jun 21, S May 6, Funny because when I was younger and saw sky writing or airplane trails I always used to think that they were a special thing only for me and no one else.
I don't know why that is just how my brain used to work, now reading this I am very interested!!! Wonderopolis May 6, Ilma May 6, I never knew that airplane engine produces exhaust, just like the car do.
I also didn't know that pilots have to learn different patterns and work on the smoking machines, and be able to write unique messages in the sky. It is also way different, how the skywriters use to do things in olden days than comparing to today.
Hung May 6, I never knew most of those facts until today. That was what i had to do for my homework. So I liked it. Great, Hung! Many contrails last just a few minutes before the frozen water turns back into vapor and the plumes dissipate. Others persist in the atmosphere for more than 10 minutes, and some spread out to become cirrus clouds.
These persistent contrails are believed to have a more significant effect on global temperatures. Another complication is that contrails can have both the heat-trapping warming effect and a separate cooling effect by reflecting light from the sun back into space. For example, contrails at night tend to have a warming effect, because they mainly trap heat coming from the Earth without reflecting any incoming sunlight.
The new research may overstate the climate-warming effect of contrails by treating them all like heat-trapping cirrus clouds, says Judith Rosenow, an aeronautical meteorologist at the Dresden University of Technology in Germany, who was not involved in the study. Satellite images have proven to be a useful tool for studying contrail patterns from commercial flights.
0コメント