Upper Tangent Arc, 22 Degree Halo, Sundog and Solar Pillar Over San Marcos, California

March 18, 2016


Photographer: Mark Ritter
Summary Authors: Mark Ritter; Jim Foster

The photo above showing a stirring upper tangent arc (top), a 22 degree halo (surrounding the Sun), a sundog (on the halo at right, at the same altitude as the Sun) and a Sun pillar (just above the Sun) was captured over San Marcos, California, just before sunset on February 23, 2016. All but the Sun pillar result from refraction of sunlight in the hexagonal ice crystals that compose cirrus clouds. The pillar is a reflection phenomenon -- sunlight is reflected off of crystals that are tipped in the viewer's direction. Also of interest is a rare upper sunvex Parry arc that can be detected immediately above the upper tangent arc.

Photo Details: Camera Model: Canon EOS 5D Mark III; Lens: EF24-105mm f/4L IS USM; Focal Length: 24mm; Aperture: ƒ/10.0; Exposure Time: 0.0040 s (1/250); ISO equiv: 100; Software: Adobe Photoshop Lightroom 6.3 (Macintosh).