Have you ever seen a plane fly overhead before, leaving behind a condensation trail that seems to linger just a little too long?  If so, you may have been exposed to chemical and biologic agents being released into the atmosphere, or so the conspiracists believe.  The theory all started in the 1990s, after the United States Air Force published a report on weather modification.  Americans started accusing the government of “spraying the US population with mysterious substances”.  These substances could be released for a number of reasons, including reduced life expectancy, weather modification, or mind control.  Chemtrails are believed to be the visible plumes of smoke from aircraft that stay visible in the atmosphere for hours longer than usual contrails.  Do we believe the government is trying to chemically control us?  What truly is being released from the planes we see every day?