Good work, Nature. Looks totally sweet. (via @GrandCanyonNPS)
Every few years, the Grand Canyon experiences something called a "total cloud inversion." Due to recent rain in the area, there has been a lot of fog in northern Arizona. Without any wind to move it out, the fog has been building up in the canyon. Warm air holds down the picturesque clouds, trapping them inside the canyon, and the result is that the Grand Canyon looks like a soothing hot tub for giants.
That iPad also looks majestically large. (via @GrandCanyonNPS)
The phenomenon usually lasts for a few days, which is plenty of time for tourists from across the world to wish they could see how it looks normally.
Here's a video from the National Park Service showing the clouds rolling in and back out again in a timelapse.
It looks like the Dementors are taking over, and then some benevolent wizard we can't see sends in his Patronus and saves us all.