We’ve all seen those white streaks trailing behind jets, creating stripes against the blue sky.
The lines are called contrails, short for condensation trails, and they appear when water vapor condenses and freezes around the exhaust from an aircraft, according to the University Corporation for Atmospheric Research.
At least that’s what science says. In recent years, a growing number of people believe that these contrails are actually chemtrails — a well-established conspiracy theory asserting that these trails aren’t made from condensation at all, but are instead chemicals being sprayed by the government. [...]