Longer lines behind planes don’t indicate ‘chemtrails’

30 April 2024
What was claimed

An image shows two different trails left by planes. The short one is a contrail, while the longer one, where the “trail extends for miles” and “lasts for ‘hours”, is a ‘chemtrail’.

Our verdict

This isn’t the case. Both images show contrails—water vapour left behind planes. Both their size and the amount of time they remain visible differs depending on atmospheric factors, such as humidity.

An image being widely shared on Facebook claims to show how to identify a “chemtrail” as compared to a “contrail” left in the sky by an aeroplane.

The post, one example of which has been shared more than 6,300 times, includes side-by-side images of two planes in the sky with differing lengths of white trails behind them.

Text within the photo identifies the longer trail as a “chemtrail”, adding the “trail extends for miles” and “lasts for hours”. While a “contrail” in the image is described as where the “trail extends for feet lasts for seconds”.

But both of the images show contrails, or condensation trails, left by aircraft.

We’ve written a number of times about conspiracy theories around ‘chemtrails’, which claim that white lines in the sky are evidence of poison being spread, or the weather being controlled, by spraying chemicals from aircraft.

But the white trails of vapour left behind by planes are actually contrails, formed when water vapour produced by aeroplane engines freezes due to high altitude, creating long, thin lines of cloud. 

The longevity of these trails doesn’t make them ‘chemtrails’ or mean they are anything other than water vapour (that may contain some tiny products of combustion). It's perfectly normal for contrails to remain in the sky for a long time, or disappear very quickly, depending on the conditions. 

If the humidity in the air is high, the crystals will remain where they are, often spreading out to leave a fluffy trail trail where the aircraft has passed and remaining in the sky for many hours. 

However, if the air is very dry the ice crystals will quickly change from a solid to a gas and become invisible. 

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Chemtrails and geoengineering

Many of the posts we see about ‘chemtrails’ link them to geoengineering—which the Met Office defines as “the deliberate large-scale manipulation of climate”.

One theoretical aim of climate geoengineering would be to combat a warming atmosphere through methods such as solar radiation modification or management (SRM), where the sun’s rays are reflected back into space to cool the planet. 

Methods which have been researched (but not put into practice outside of small-scale experiments) include stratospheric aerosol injection, which could be carried out through adding sulphur dioxide particles to the atmosphere to reflect sunlight before it can be absorbed as heat, mimicking the effect of a volcanic eruption.

There has been a de facto moratorium (which is not legally binding) on solar geoengineering since 2010, with exceptions for small-scale scientific research studies. And experts have since called for firmer restrictions on states engaging in climate geoengineering.

The UK government said in 2020 it had not deployed any solar radiation management techniques, and had no plans to do so. 

However, some countries elsewhere in the world have used other weather modification technologies such as cloud-seeding to generate rainfall or snow.

Recent major flooding in Dubai prompted misleading speculation online that it was caused by cloud-seeding, which has been used in the United Arab Emirates to help address water shortages.

Image courtesy of Nestek

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