Sierra Nevada Low Rainbow

November 19, 2015

Storm over eastern sierra and rainbow m

Photographer: Glenn McCreery
Summary AuthorGlenn McCreeryNovember 2015 Viewer's Choice

While driving along the eastern slope of the Sierra Nevada range of California on the morning of October 18, 2015, I came upon this rainstorm and beautiful display of a low rainbow. I was fortunate that the morning Sun was not yet obscured by these approaching rain clouds -- the camera was facing northwest. Note that the Sierras act as a giant water trap, wringing almost all of the moisture from Pacific storms as they move eastward. In fact, the western boundary of Death Valley National Park, the hottest, and one of the driest places on Earth, is only approximately 25 mi (40 km) to the east of this location.

In order for a rainbow to be detected at ground level, the Sun cannot be higher than approximately 42 degrees above the horizon (0 degrees). Therefore, low rainbows like this one are only observed from level ground when the Sun is fairly high in the sky. Using the Sun and Moon altitude/azimuth web-table of the U.S. Naval Observatory with nearby Lone Pine, California as the location, October 18, 2015 as the date, and 10:45 a.m. Pacific Daylight Time as input, I determined that the Sun’s altitude above the horizon was approximately 37 degrees. Within an hour, the Sun’s altitude above the horizon would be greater than 42 degrees, and thus this rainbow could no longer be viewed.

Photo Details: Camera Model: Canon EOS 5D Mark II; Lens: EF24-105mm f/4L IS USM; Focal Length: 47mm; Focus Distance: Infinite; Aperture: ƒ/8.0; Exposure Time: 0.0031 s (1/320); ISO equiv: 100; Software: Adobe Photoshop CS5 Macintosh.