Version v2: Fixed visible seam and changed to more fitting name. Used to be NBSky Medium Clouds 1.
2k Medium Cloud Sky image. Derived work from public domain sky photos. See license text for usage info. TLDR of the license text:
No modifications, no using in routes or sessions distributed over jointedrail.com, rypi.com, thebackshops.com or join-together.de, and no using in payware marketed outside store.trainzportal.com and store.steampowered.com without contacting the original author and asking for permission.
If you want to be able to do whatever go on a lookout for the texture parts and make all the Trainz adaption work yourself.