Weather conditions in Arizona's Grand Canyon last week gave rise to a rare phenomenon called total cloud inversion. Last Friday, and again on Sunday, the ground apparently released some of its heat rapidly enough at dawn to create a layer of cool, damp air inside the canyon, trapping it beneath the unusually warmer sky above the canyon walls and filling the space with a sea of fog. Park officials said the phenomenon is a once-in-a-decade occurrence and ran to capture these fantastic photos. (If your display can support it, I recommend selecting the 1280px option below.)