Dean M. Chriss
Frosty Morning along Obsidian Creek, Yellowstone National Park
(Click image to enlarge)
Temperatures in Wyoming's Yellowstone National Park can get chilly in October.
On this particular morning it was 11º F (-11.6 ºC). Fog rising from the warmer
Obsidian Creek as it flows lazily through a meadow coats each blade of grass in
a crystalline cover of frost.