THE GRAND CANYON doesn’t need any help being amazing. But every several years, a rare phenomenon fills the massive canyon up with fog, turning the wonder of the world into an otherworldly wonder.

The phenomenon is called a “total cloud inversion,” and it happens when cold air in the canyon is trapped in by warm layer of air above it, forming a sea of clouds. A total cloud inversion typically only happens every several years, but coincidentally, it has happened twice in the past six weeks.

Featured photo by Grand Canyon NPS.