...
Therein, often to Minnis' amusement, lie the seeds of conspiracy. Some people look at contrails and instead see "chemtrails," telltale marks of something suspicious.

"There are tanker planes leaving airline terminals all over this country every day," one person wrote to counter Minnis' explanation that contrails are frozen water vapor. "They are loaded with chemicals, which they spray in the skies over heavily populated areas."

"Why do some planes fly by and the contrails disappear while others leave those long contrails that expand and stay?" another wondered. "The strange thing if you watch closely is that it's the same planes making what looks to be some kind of grid."

Thursday night, the Discovery Channel was to explore the conspiracy theory behind "chemical contrails," and they interviewed Minnis to shoot it full of holes. He's slightly anxious about the show and, because of that, watched a similar special about radioactive fallout from bomb tests in the 1950s.

"It looked like they treated the scientists pretty straight," he said. "They came on to me like you're going to be believable, but who knows."

Minnis and NASA study contrails for the same reasons they study the clouds and the weather: NASA flies things, and if something affects the skies, they need to know how.
...