dandelO, nice work! I wondered if even the thin trails were procedural, nice to see that they are, and I expected nothing less from you.

Seeing this image I am suddenly realizing that though we see contrails everywhere in real life, we seldom (if ever) see them in TG images. I suppose perhaps TG is the world as we would *wish* it to be...
Also, why do we look for such extreme explanations for this phenomenon when very simple, clear, scientifically plausible explanations are quite rational and satisfying?
"Contrails (/ˈkɒntreɪlz/; short for "condensation trails") or vapor trails are long, thin artificial clouds that sometimes form behind aircraft. Their formation is most often triggered by the water vapor in the exhaust of aircraft engines, but can also be triggered by changes in air pressure in wingtip vortices or in the air over the entire wing surface.[1] Contrails are made of water in the form of a suspension of billions of liquid droplets or ice crystals."
You can test major elements of these proposed explanations yourself, in fact. Combustion of petrofuels results in water vapor as a major exhaust component (ever see water drip out your car's tail pipe?), exhaust also contains aerosols/particulates around which water vapor can condense (see: exhaust from a big rig truck), and condensation happens faster and more readily at cold temperatures or at the interface between hot and cold (see: bathroom mirror fogging, condensation on cold glass on a hot day). Honestly this is almost at the level of common sense...
And that's the last I'll say on the subject. No more politics in the Terragen area of discussion please. If you *must*, do it in Open Discussion, but we also strongly discourage it there too (i.e. in general).

- Oshyan