Sun Halo and Rainbow Bridge
September 06, 2016
Nature offered a heavenly one-two scenic punch during a Lake Powell boat trip and hike into southern Utah’s Rainbow Bridge National Monument: A majestic 22 degree Sun halo overhead and the earthbound majesty of the preserve’s towering namesake arc of stone.
Rainbow Bridge is silhouetted in the top photo, taken on August 21, 2016, because we’re looking toward the Sun. The 22 degree halo, formed from sunlight refracting through ice crystals in cirrus clouds, is named for its angular distance from the solar disk, 22 degrees or a little more than two fists held at arm's length. So make sure to protect your eyes whenever observing these halos.
Formed in Navajo sandstone on a base of harder Kayenta formation sandstone and shale, Rainbow is one of the world’s largest known natural bridges — arches created in large part by flowing water. The bottom photo showcases the bridge in more natural light, with visiting tourists offering a size comparison. The landmark is most easily accessible today by boat via man-made Lake Powell, named for 19th-century explorer and scientist John Wesley Powell. As drought has lowered the level of the reservoir, created by the Glen Canyon Dam on the Colorado River, a 2.5 mi (4 km) round-trip hike is currently required to get to Rainbow Bridge from a floating dock.
Hidden in Bridge Canyon below landscape-dominating 10,388-ft (3,166 m) Navajo Mountain, a dome-shaped laccolith, Rainbow Bridge rises 290 ft (88.4 m) from its base. The sturdy span — 42 ft (12.8 m) thick and 33 ft (10 m) wide, according to the U.S. National Park Service — arcs 275 ft (83.8 m) over the narrow canyon’s channel. Anciently, a stream flowing off Navajo Mountain meandered around a Navajo sandstone fin at this site. Eventually, water cut through the barrier and the sculpting of Rainbow Bridge via eccentric stream erosion was well under way.
Photo Details: Top - Camera Model: NIKON D3200; Lens: Tokina AT-X 124 AF PRO DX II (AF 12-24mm f/4); Focal Length: 12mm (35mm equivalent: 18mm); Aperture: ƒ/13.0; Exposure Time: 0.0013 s (1/800); ISO equiv: 100. Bottom: Same except - Focal Length: 14mm (35mm equivalent: 21mm); Aperture: ƒ/11.0; Exposure Time: 0.0020 s (1/500); ISO equiv: 400.