Hey @rombout thanks for your feedback.
I used different methods for the snow on the rocks and ground.
For the snow on the rock face, I first sculpted the rock. From there I duplicated the rock, smoothed it, and sculpt it further to turn it into snow. Finally I added the snow material to it.
For the snow on the ground, I first sculpted the general shapes: small hills and valleys. Then I added the details like the waves sculpted by the wind or the traveler’s track with bump textures applied with Blender adaptive subdivision/ micro-diplacement feature.
Concerning the lighting you’re completely right. I didn’t use the same picture for the sky background as for the HDRI lighting the scene. This was on purpose, as I thought it’s creating a more interesting picture, with more contrast where I wanted in the sky. This difference in lighting was not very noticable… at least I thought it wasn’t, but you noticed it haha