December 11 was a weird day at the Grand Canyon.

This image, captured by Maci MacPherson with the National Park Service, looks like some alien cloud world and definitely not arid Arizona, but in a rare weather display, low-lying clouds nearly filled the entire Grand Canyon. This event is actually supposed to be extremely rare. However, a similar phenomenon occurred last year in December as well. Only this time, the park service time lapsed this seemingly otherworldly event.

What makes this cloud-filled wonder possible is a process called inversion, where warm air on top of the Canyon traps cooler air down below, creating the visible cloudstew in the world's largest mixing bowl.


What was described last year as a "once in a lifetime" event now seems to have given us all an encore. Grand Canyon, now you're just showing off. [NPR]


Images via Maci MacPherson/National Park Service