Visitors to Mather Point at Grand Canyon National Park, Ariz., look out over a rare total cloud inversionin 2013.  (Erin Whittaker/The Associated Press)
{"Image ImageDescription": "In this Friday Nov. 29, 2013 photo released by the National Park Service, visitors to Mather Point at Grand Canyon National Park, Ariz. look out over a rare total cloud inversion. The phenomenon, caused by cold and warm air masses interacting, left the Grand Canyon peaking above a sea of clouds. (AP Photo/National Park Service, Erin Whittaker) LA101", "Image Artist": "Erin Whittaker"}