Proof that it's not condensation vapor.
Two airplanes flying in parallel: the first, unlike the one on the right, does leave a polluting trail under the same atmospheric conditions of pressure, temperature, humidity, etc.
VIDEO:
Proof that it's not condensation vapor.
Two airplanes flying in parallel: the first, unlike the one on the right, does leave a polluting trail under the same atmospheric conditions of pressure, temperature, humidity, etc.