Bethany Rothwell takes to the sky and assesses the supposed impact of jet plane ‘chemtrails’.
It’s a gorgeous sunny day. You hear a plane passing overhead, look up at the sky and what do you think about? The pretty patterns of white streaking across the blue sky? Plans for your next summer holiday? Or the government’s ruse to shower us with psychologically-manipulating or weather-modifying chemical agents?
The term “chemtrail” is a clever combination of the words “chemical” and “contrail”. What’s perhaps not so clever, is the belief that these trails left in the sky by aircraft are anything more than simple condensation. The reason contrails are produced can be easily explained. Jet engines emit very hot, humid air. At high altitudes, the surrounding air is very cold – usually lower than -40°C – and at very low vapour pressure. When the hot air comes into contact with its surroundings, the water vapour quickly condenses to form visible clouds, which trail off the back of aeroplanes as they streak through the sky.
The theory argues that, while normal contrails should dissipate from the sky fairly quickly, harmful chemical compositions cause the observed trails to linger for much longer. However, the duration of contrails in the sky depends on a large number of atmospheric conditions. For example, if the atmosphere is almost saturated (if it contains nearly the maximum amount of water vapour it can hold at that temperature and pressure), the additional vapour from the contrail will take a long time to dissipate, while if the atmosphere is dry, dissipation will be much faster. The persistent trails are really just the result of the atmospheric condition, and nothing at all to do with added chemicals.
Chemtrails are also supposedly characterised by the way they spread out across the sky, perhaps to block out sunlight, or to ensure the full population beneath receive a dose of the chemical poisons. This is another absurd claim that has a simple, logical explanation. Vertical spreading-out is the result of different-sized ice crystals in the contrails descending at different rates. Horizontal spreading across the sky is caused by wind, with variation in wind velocities at different altitudes causing contrails to spread several kilometres across the sky.
Under certain atmospheric conditions, and with lots of air traffic, it is common that contrails can entirely overcast the sky – this really is nothing to worry about!
Images and videos claiming to show evidence for the toxic trails have been circulating the internet in the last decade, with entire websites dedicated to spreading the theory, and the fear. For example, photos of the inside of the prototype Boeing 747 plane showed
large barrels in the passenger area—it was claimed that these were for aerosol dispersion purposes. In reality, these were simply used to imitate the weight of passengers or cargo on test flights, with water being pumped between the barrels to simulate different centers of
gravity. Another completely logical explanation for a completely illogical claim.
A 2011 study showed that in the UK, Canada and the US, 16.6% of people either fully or partially believe the conspiracy theory, and it is no surprise that this theory would cause fear and anxiety amongst its believers. The fact is that every characteristic linked to
chemtrails has been disregarded by atmospheric experts as completely
normal features of contrails under different atmospheric conditions, and so they pose no direct threat to public health. Spreading this fear and anxiety around is simply unnecessary, and potentially dangerous. Sure, our governments may be corrupt and dishonest in a number of ways, but don’t these crazy theories just seem a bit too extreme?