In this video is a pilot saying that he sprays the sky with Silver Iodide as a way to manipulate the weather.
He says Silver Iodide is safe. EPA says differently...
"Under the guidelines of the Clean Water Act by the EPA, silver iodide is considered a hazardous substance, a priority pollutant, and as a toxic pollutant". Silver Iodide is an inorganic compound.
The question as to whether chemtrails exist and are happening the answer is absolutely yes.
The answer to what these chemtrails are used for and what their effects are is a bit more complicated...