22-Degree Halo Above Meaford, Ontario

May 22, 2011

Photographer: Heather J. Renyck; Heather's Website
Summary Author: Heather J. Renyck; Jim Foster

This photo of an enchanting 22-degree halo was taken in southern Ontario, Canada around noon on April 13, 2011. I was initially gazing at a cirrostratus cloud deck that appeared as a giant ray of whiteness rising above the horizon but then noticed the halo, high in the sky. Unlike rainbows, which cannot be seen at midday in the tropics and mid-latitudes, halos can be observed at noon or midnight (around the Moon). Sunlight refracting through randomly oriented, hexagonal ice crystals in cirrus clouds give halos their circular appearance. Twenty-two degree halos aren't as vividly colored as other halo phenomenon such as circumzenithal arcs, but they can exhibit modest color if the ice crystals are greater than about 0.025 mm in diameter. Always make sure to protect your eyes when looking toward the Sun.

Photo details: Camera Maker: OLYMPUS IMAGING CORP.; Camera Model: E-510; Focal Length: 9.0mm; Aperture: f/11.0; Exposure Time: 0.0020 s (1/500); ISO equiv: 100; Exposure Bias: -0.70 EV; Metering Mode: Matrix; Exposure: Creative Program (based towards depth of field); Exposure Mode: Manual; White Balance: Manual; Light Source: Cloudy; Flash Fired: No (enforced); Orientation: Normal; Color Space: sRGB.