When it reaches the dew point, a visible cloud forms. Condensation trails behind aircraft are simply clouds. All three components are created, and when conditions are just right, these contrails will appear behind every plane in that part of the sky.
Jet engines produce an incredible amount of heat , along with water vapor and other combustion exhaust particles like carbon dioxide. This exhaust is shot out the back of the jet engine into the surrounding cold air. The atmosphere at high altitudes is frigid. Most airliners fly between 30, and 38, feet above sea level , where the temperatures range between and degrees Celsius. At these temperatures, the water vapor will condense into water droplets, which will become ice crystals quickly.
Like the upper-level cirrus clouds at these altitudes, the ice crystals will blow and scatter with the wind conditions. If the upper-level winds are calm, the contrails may remain intact for a long time. While it is true that the contrails contain pollutants, just as all combustion engines leave pollutants when operating, the contrails are not made of smoke, visible pollution, or chemicals.
They are clouds just like natural cirrus clouds, made of ice crystals suspended in the atmosphere. A specific set of atmospheric circumstances have to line up to create an exhaust contrail. They divide contrails up based on how persistent they are in the atmosphere. Sign up for our email newsletter. Sign Up. Support science journalism. Knowledge awaits.
See Subscription Options Already a subscriber? Create Account See Subscription Options. Continue reading with a Scientific American subscription. Subscribe Now You may cancel at any time. Welcome back, Ryan!
We also want to make sure that we are representing the scientific evidence behind this WONDER, which is how the exhaust trails are formed. This is why we chose to remove part of your posting.
Contrails do exist like Wonder is stating, but they fade fairly rapidly after an airplane paases an area.
A Chemical Trail aka ChemTrail that is being sprayed, exhausted, etc, by aircraft does not dissipate. Can Wonderolis explain what or why aircraft, more specifically airplanes, are spraying ChemTrails? Those are great questions, Joe! Maybe you could do further research on the topic at your library.
Hi Amy! Some scientists are concerned that the exhaust trails may affect Earth's climate. There are many different beliefs about this topic. That's true, Mohit Dagar. Why do you think that is? Thanks for sharing your thoughts, Jan! We think you're right, that it's not normal procedure to fly back and forth and completely cover the sky with contrails -- usually planes are just passing through, getting from point A to point B!
We think you're right, that it's not normal procedure to fly back and forth and completely cover the sky with contrails" -So why keep doing it if you think its not normal, STOP doing it let nature takes its course!!!! Thanks for sharing your thoughts, Jeremy. Excellent argument, Laney! Keep in mind the reason contrails linger in the sky so long has a lot to do with the temperature at that height.
If this was a normal byproduct of jet plane exhaust, it would have been in the sky prior to the late 's but it wasn't.
The frequency and number of trails in the sky has greatly increased since they started out as a rare phenomenon in the last 's.
Hi Rich! It could be used for communication purposes! Some airplanes even write words in the sky with their tracks! Have you ever seen that before? Hi EH! Planes leave the lines behind them as the exhaust leaves the engine and combines with the air vapors!
Hi there, Tera, thanks for joining us at Wonderopolis today! We sure are glad that you commented on our flying Wonder, too! Those artificial clouds in the sky are actually exhaust gases from the airplane. You might have seen exhaust gases from the tailpipe of a car-- the same is true for airplanes!
We hope you have a great day, Tera! Please come back and visit us soon! We are undergoing some spring clearing site maintenance and need to temporarily disable the commenting feature. Thanks for your patience. Drag a word to its definition. You have answered 0 of 3 questions correctly and your score is:. Want to add a little wonder to your website? Help spread the wonder of families learning together. We sent you SMS, for complete subscription please reply. Follow Twitter Instagram Facebook.
Why do airplanes leave tracks in the sky? What are contrails? How do pilots use planes to write in the sky? Tags: See All Tags airplane , artificial , cloud , cloudy , condensation , contrail , evaporating , exhaust , pilot , plane , sky , skywriting , track , trail , vapor , water. Not exactly… Skywriters use small airplanes equipped with special smoke machines to fly in special patterns to create written messages visible from the ground.
Wonder What's Next? Try It Out Ready to make your own contrails? Don't worry, though, you can still have fun checking out one or more of the following fun activities with a friend or family member: Do you ever make homemade cards for your friends and family members on their birthdays?
There's nothing quite like a heartfelt message written by hand in a card you made yourself. Of course, paper limits you a bit in terms of the impact your message can have.
But what if you had the whole sky as your canvas? What would you skywrite to a friend or family member if you had the chance to write any message in the sky for them to see? Think about it and then tell that person what you would write if you could write in the sky. You never know when you just might make someone's day! Is it cloudy outside today? We hope so! Because this activity requires some clouds. Head outside with some friends or family members and lay out a blanket so you can comfortably gaze at the clouds as they cross the sky.
What shapes do you see? Pick out a certain area of the sky and see what you can see. Do your friends or family members see the same things you do?
Compare your observations. How are they similar? How are they different? Have fun cloudgazing and using your imagination to give the random clouds some meaning! If you're up for a challenge, try this fun experiment at home with just a few simple supplies.
Grab a clear plastic 2-liter bottle, matches you'll need an adult to help with this experiment and some warm water. Just follow the directions to create your very own Cloud in a Bottle! Did you get it? Test your knowledge. 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. The segment answers viewer weather questions, explains weather phenomena and reveals interesting weather stats. Weather Whys: Why do airplane contrails form on some days but not others?
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