The Grand Canyon gets a rare visitor: massive fog 

The fog sweeping in around Mather Point (top photo by Erin Whittaker) made for a very different view.

Visitors to Grand Canyon National Park on Friday and Sunday were treated to a rare — and eerie — sight: The steep canyon gorges and valleys were filled with a thick carpet of fog.

The weather phenomenon that caused the eye-popping sight: A temperature inversion, according to the Grand Canyon Facebook page, which noted, "Rangers wait for years to see it. Word spread like wildfire and most ran to the rim to photograph it. What a fantastic treat for all!"

Pictures of the bizarre sight quickly spread on the Web. Commenters on Facebook took the view in from afar. "People overuse the word 'amazing'... This truly is AMAZING," posted Linda Dyar Papa.

Gwen Vaughn Willis added, "I would love to be able to stand there and look at that view. Awesome!"

(Photo: National Park Service)

Grand Canyon park ranger Erin Whittaker, who took the shot of the fog at Mather Point, described the sight as "moody" and "mysterious," adding, "It's the idea that you can't see something that's so big when it's fogged in is amazing."

The temperature inversion causing the fog is fairly uncommon, National Weather Service meteorologist Megan Schwitzer told Yahoo Travel on the phone from Flagstaff, Ariz.

The forecaster explained that the warmer air from above is trapping the colder air — and the fog — near the ground. "The unusual part this time is the amount of moisture for the fog to form," Schwitzer said. "I wouldn't say we haven't seen it before, but it's pretty seldom, pretty rare."

Click above to see more Grand Canyon fog photos.