Some conspiracy theorists believe that contrails formed by jet exhaust are part of a
secret government plot to alter the atmosphere.
Credit: Mick West/UCI
If you're fascinated with conspiracy theories, you've probably come across one involving those streaks that jet aircraft leave behind them in the sky, as particles from the engines' exhaust plume cause water vapor in the air to condense around them and form ice particles. In aviation, those streaks are called "contrails," short for condensation trails, and they're a phenomenon that's been observed since the beginnings of jet-powered flight. (Here's a Federal Aviation Administration FAQ on them.)
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Nevertheless, to conspiracy buffs, nothing is that simple or innocuous. Some believe that the streaks are what they call "chemtrails," and that they're part of a sinister, clandestine government plot to modify the weather, or else some sort of biological warfare weapon. (From the Committee for Skeptical Inquiry, here's a guide to those accusations.) One poll a few years back found that nearly 17 percent of Americans thought it was either true or partly true that the government was involved in atmospheric alteration, and the chemtrails conspiracy theory even has been promoted by celebrities such as Kylie Jenner and the late Prince.
