Ohio Lunar Halo

October 13, 2012

LunarHalo093012_11_30pmChumackHRweb (2)

Photographer: John Chumack; John’s Web site
Summary Authors: John Chumack; Jim Foster

The photo above shows an eye-catching lunar halo as seen from my home in East Dayton, Ohio, on September 30, 2012 – two days past the Harvest Moon. The view is toward the southeast. Randomly oriented, pencil-shaped ice crystals in the thin cirrus overcast triggered this classic 22 degree halo. As moonlight (or sunlight) passes through a side face of these crystals it’s refracted 22 degrees from the initial angle of incidence before exiting through an alternate side face. Because Mother Nature is sometimes surprising, I always go out at look at the night sky before I go to bed, even if the forecast calls for cloudy skies.

Photo details: Camera Maker: Canon; Camera Model: Canon EOS DIGITAL REBEL XSi; Lens: 8mm fisheye; Aperture: f/4.5; Exposure Time: 4.000 s; ISO equiv: 400; Exposure Bias: none; Metering Mode: Matrix; Exposure: Manual; Exposure Mode: Manual; White Balance: Auto; Flash Fired: No (enforced); Orientation: Normal; Software: Adobe Photoshop 7.0. Taken at approximately 11:30 p.m.