Everyone has seen the cloudy white trails across the sky that sometimes follow jet aircraft. It’s easy to imagine that they are sign of chemicals raining down from above. Among certain conspiracy-minded folks they have been dubbed ‘chemtrails’ and are believed to be evidence of secret government projects with various nefarious purposes, most often involving weather modification or climate engineering.
What’s the real reason? These condensation trails, or contrails, are simply what happens when the chemistry of burning jet fuel meets the chemistry of air. The video above from the American Chemical Society sets the record straight.
Transcript from the video above:
It’s easy to look at the white trail behind a jet aircraft and imagine all manner of chemicals raining down from above. Could they be harmful? Could it be some sort of conspiracy? The truth is out there. It’s just in the form of some pretty straightforward chemistry.
Chemtrails are made mostly of water, because that’s what happens when the chemistry of burning jet fuel meets the chemistry of air.
Here’s how that works. Jet fuel is mostly made of stuff like these molecules here, these are hydrocarbons, which are chains or rings of carbon atoms with hydrogen taken off the sides, and there are a whole bunch of different kinds in jet fuel.
The chemical bonds holding these molecules together are a source of energy, which gets released by burning and when thrown out the back of the engine propels the jet plane through the sky.
But the carbon and hydrogen has to go somewhere when the bonds are broken. They mix with oxygen creating carbon dioxide and water. There’s a little bit of extra stuff in there too, like nitrogen and sulfur. The sulfur will react with the oxygen to form sulfur dioxide.
The products are expelled from the jet engine and trail along behind the plane, but water is clear, so why is it leaving a visible trail? What’s going on in the jet engine?
They’re basically the same chemical reactions as in the engine of a gasoline-fueled car on cold days when you can see the exhaust coming out of the tailpipe. That’s mostly water.
The same thing happens with water leaving the jet except much more extreme at a commercial plane’s cruising altitude of 35,000 feet. The temperature is around minus 50 degrees Celsius. You know, minus 50 isn’t unheard of in Antarctica, well it’s still pretty flippin cold. Depending on the exact conditions, the water can freeze into ice crystals or condense into liquid droplets. The sulfur impurities really helped get those droplets going, but whether it’s water or ice, these puffy white trails are made up of bits of h2o scattering light so we can see it, which means they aren’t chemtrails, except in the sense that water is the chemical. They are more technically known as contrails, short for condensation trails. The scientific community is pretty well agreed on the subject of chemtrails actually being contrails.
One study surveyed experts in the field of atmospheric chemistry and I asked them whether they had in their entire career ever seen evidence for a secret, large scale atmospheric spraying program or “slack” for short. 99% of the experts surveyed said no, which is way more consensus than four out of five dentists telling you to chew with certain branded gum.
So unless they’re crop dusting or cloud seeding, all those jets are leaving behind is their own watery exhaust.
Related reading: Containing the contrails
Curated content from the editorial staff at Cosmos Magazine.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.