Chemtrails Or Contrails?

"Contrail" is an abbreviation for condensation trail — the water vapor or ice crystals trail emitted from aircraft engines. However, some people believe that some of these trails contain not water vapor and ice crystals, but chemical or biological agents. There's no agreement on precisely when or where the idea of chemtrails first emerged, but the feeling among many researchers is that it's a disturbing trend in the United States.