Pilesgrove Circumhorizontal Arc
June 25, 2009
I noticed this colorful strip of sky while watching my son's baseball game near Pilesgrove, New Jersey, on May 23, 2009. It’s a circumhorizontal arc (CHA) and was part of a fetching halo display that lasted almost 45 minutes close to mid-day. CHAs may result when sunlight is refracted through similarly oriented, hexagonal ice crystals, which are most often found in cirrus clouds and also in jet condensation trails (contrails), as shown here at right. They only grace the sky when the Sun is high up – near the zenith. In the mid-latitudes this restricts their appearance to late spring and early summer.