22 Degree Halo and 46 Degree Halo

May 29, 2012


Lisa Gonnelli
Summary Author Lisa Gonnelli; Jim Foster

The photo above showing a 22 degree halo and what may be a 46 degree halo (faint arc at top) was taken from Pilesgrove, New Jersey on March 10, 2012. Whereas the frequently observed 22 degree halo is formed by the minimum deviation of refracted sunlight through 60 degree prisms (hexagonal ice crystals); 46 degree halos result from minimum deviation through 90 degree prisms. Both halosAnother view are formed in the same poorly aligned ice crystals, but because a smaller amount of light emerges through the 90 degree prism and since the 46 degree halo is more readily dispersed (spread out across the sky), it’s considerably dimmer than the smaller 22 degree halo. 46 degree halos are quite rare and can be easily confused with more colorful supralateral or infralateral arcs. Always protect your eyes when looking for these halos, particularly the 22 degree halo.

Photo details: Camera Maker: OLYMPUS IMAGING CORP.; Camera Model: E-500; Focal Length: 17.0mm; Aperture: f/9.0; Exposure Time: 0.0050 s (1/200); 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 (Auto); Orientation: Normal; Color Space: sRGB; Software: Adobe Photoshop Elements 8.0 Macintosh.