Sea of clouds cover the Grand Canyon in rare weather event

Imagine showing up for a once-in-a-lifetime chance to view the Grand Canyon in Arizona only to find the deep ravine completely covered by clouds. If you went today, that’s what you saw — a rare total cloud inversion just below the rim. The unusual weather phenomenon usually happens every few years, but this is the second year in a row.

The clouds materialize when cold air gets caught between the Earth’s surface and warmer air above, according to the National Weather Service. Weather forecasters expect these clouds to dissipate gradually as a cold weather system moves in, bringing the first snow of the season to the national landmark.

Watch a time lapse video of the clouds beginning to close in over the canyon several days ago: