Halo Display Above Lancaster County, Pennsylvania

December 08, 2013



PhotographerBeth Katz
Summary Author: Beth Katz

This halo display was observed over the town of Letort in Lancaster County, Pennsylvania, around 12:30 p.m. on November 4, 2013. The Sun's altitude was approximately 34 degrees. On the top photo, the bright colorful arc with the outstretched arms that dip slightly, just above the tree at center, is an upper tangent arc. It’s tangent to the 22 degree halo; the faint color-tinged circle just below it. Atop the upper tangent arc is a suncave arc known as the Parry arc. Colorful sundogs are found on either side of the Sun (blocked by the tree). They’re located on the parhelic circle; the white band of light stretching across the sky at the same solar altitude.

The bottom photo shows a better view of the parhelic circle as well as a 120 degree paranthelion that was also part of this display. Always be sure to protect your eyes when looking toward the Sun, but look up whenever thin, cirrus clouds streak the sky. See also the Earth Science Picture of the Day for November 12, 2009. It features a HaloSim ray tracing simulation giving the locations of most of the arcs mentioned above.

Photo details: Apple iPhone 5; 4.1mm focal length; f/2.4 aperture, 1/2584 sec. exposure; ISO equivalent 50.