In this case one could identify the airplanes using Flightradar24 and then, if the anti-chemtrail movement is so big and vibrant why not organize a distributed investigation and have people go to the airports to document these planes (document any strange equipment on the planes and whether they are passengers planes with passengers...)
Today here in Finland all contrails look like this picture below because of the atmospheric conditions (cold dry air). I could have predicted it almost a week ago too.
Another thing is that most of the air traffic I see to the south of me over the sea are the Russia<->Kalingrad traffic since they now can't fly over over countries. That traffics contrail/persistent-contrail days is in sync with other airplanes... Which would mean they for some reason somehow co-operate and "chemtrail" on the same days.