A plane zips across the sky, leaving in its wake a long line of white cloud. There is a conspiracy theory that swears this is the government spraying the world with “mind-control agents” for nefarious means. A little bit of science reveals the truth.
The white line, called a condensation trail, or contrail, is made of nothing but cloud. They are no different than any other cloud in the sky. Just tiny droplets of water that float through the air. These contrails are created behind a jet plane as it literally rips through the sky.
The exhaust from a jet engine spews out a lot of hot air, along with water vapour, soot, and a few other chemicals. As the body and wing of the plane move through the air it creates a lot of turbulence in its wake, like a speedboat moving across a calm lake. As a result the cold air in the upper sky is violently churned with the engine exhaust. It’s this mix that often provides the right environment for clouds to form.
The cold air in the sky causes the warm water vapour to condense into droplets around the tiny particles of soot. If the air around the contrail is dry, it can suck up the moisture like a sponge fairly quickly, and the trail fades away. However, if the air is humid the contrail can be seen as a sharp line across the sky for hours as it slowly spreads out.
It’s actually the exact same process, though on a larger scale, as when you exhale on a clod day and can see your breath. That’s the warm humid air from your lungs condensing as it meets with the chilled outside air.
So that trail is not brain-numbing chemicals. It’s not smoke, or even pollution of any sort really. (Any jet exhaust seems insignificant compared to the number of cars on the road) It’s nothing but a harmless fluffy cloud. Although, there have been some studies asking questions about whether the additional blanket of clouds may be warming up our world.
Questions are good. Questions can be dangerous! Questions can sometimes make governments wish they were spraying mind-altering cocktails in the air.
- Source: Contrails – Cooperative Institute For Meteorological Satellite Studies, University of Wisconsin-Madison