That the Planet Alpine skydome?
No, I buy backdrops at renderosity. I think she uses daz content and some of bryce, as I’ve noticed some elements (like moongate and such).
The backdrop is called. Winter landscaps by Melkor. IT is possible she uses some sort of skydome, although this set predated planet alpine so I’m not sure whence its origin.
The lighting is Lantios Core lighting by lantios
Then I touched it up with some snow brushes bought at rendo to add more foregound snow and an icey overall feel to the pic.