Post comparing chemtrails and contrails shows two examples of contrails

A Facebook post has shared an image of two white vapour trails in the sky, which it claims shows “the difference between a contrail and a chemtrail.”

This is a reference to the “chemtrails” conspiracy theory, which claims that white lines of vapour left behind by aeroplanes are evidence of chemicals being sprayed either to spread poison or control the weather.

Chemtrails do not exist, and we’ve written about this conspiracy theory several times before as part of our work identifying online misinformation. 

In fact, both of the vapour trails in the image are examples of condensation trails—or contrails— which are formed when water vapour produced at high altitudes by aeroplane engines freezes as it is released into the cold air surrounding the aircraft.

The frozen vapour leaves a trail of tiny ice crystals which, depending on the humidity of the air, either change directly from a solid to a gas and become invisible after a few minutes, or remain as water droplets or ice crystals, creating the white lines often seen in the sky, which can remain visible for several hours.

The image shared on Facebook shows what appears to be a shorter, thinner line of vapour, alongside a longer, thicker line. In reality this difference is not because the vapour trails are caused by different substances, but because the appearance of contrails can be affected by a number of different factors. 

The science magazine Scientific American states: “Depending on a plane's altitude, and the temperature and humidity of the atmosphere, contrails may vary in their thickness, extent and duration.”

Image courtesy of TXLopez