Yesterday's visitors to the Grand Canyon missed seeing its great depths, but perhaps witnessed something even more awe-inspiring. Due to a rare weather event known as a total cloud inversion, the canyon filled nearly to the brim with a sea of clouds—a result of warm air forcing clouds down into the canyon where wind can't whisk them away, the AP reports. The Daily Mail notes that as a result of the phenomenon, which occurs every few years, "the Grand Canyon appears to be sitting on top of the clouds." The National Weather Service expects the clouds to clear out over the weekend. (More Grand Canyon stories.)