Wyoming in winter is a special place. Yellowstone covered in snow is quite different from the warm, sunny version most people see in the summer. Mammoth Hot Springs emitting steam and creating fog has a mystical appearance. It looks as though it might be a locale for "Lord of the Rings".
The waterfalls don't give up their freedom easily and although encased in snow and ice they usually manage to keep moving.
One feels almost like they are walking in a snow globe when there's fresh, soft snow on a bright sunny day.
Scenic aerial flights are not currently allowed over the parks but permits for research and photography are sometimes issued. Seeing the Grand Prismatic from the air is a rare and wonderful sight. God's view of Grand Teton peak near Jackson marks another incredible experience.