What are chemtrails?

. “ “Chemtrails” are exhaust patterns left in the atmospheric wake of jet/turbine-powered airplanes. …”
… these are, in fact, correctly called “ contrails “ which is a contraction of “ condensation trails “, or “ vapour trails “.
. The term “ chemtrails “ is indeed a descriptive term used in the context that you convey in your second sentence:

“… Some people believe they are atmospheric chemical tests conducted on the populace to determine the effects of some kind of mind control gas lol “ . ….. however, in my opinion this is essentially just one of those all too common “tongue-in-cheek” pseudo-paranoic conspiracy theories. . Nothing to see here folks. .

Thank you for… oh I forgot.