Re: Ethylene ?

From that same link:

Secondly, and very popular these days, are the fuel additive contrails adding an
aerosol content to the troposphere and lower stratosphere. These trails do last
slightly longer than usual and are brilliantly white when viewed from below.
Commercial aircraft have been added to this fleet of atmospheric workers in
addition to many previously retired airliner MD-80's. These contrails can also
become very persistent in a favorable prefrontal storm environment. Sound
dampening equipment has been installed on these planes so many pass overhead on
the quiet. You have got to look up to see them. Tweet