Subsun and Subparhelia

June 23, 2003


Provided and copyright by: Tim Martin, Greensboro Day School
Summary authors & editors: Tim Martin

This image was captured on a flight over northern Indiana. It was actively snowing while taking off from Southbend, IN airport. Shortly after take-off the aircraft emerged from the low altitude nimbostratus clouds – a typical scenario for lake effect snows. I initially thought I viewed and photographed a brilliant sun-dog through breaks in the clouds. Careful consideration of the geometry of the situation quickly led me to believe this was not a conventional parhelic display as sun dogs are typically at the same altitude as the sun. Since photographing this unusual atmospheric display in December of 1999, a description of exactly what I saw had eluded me. A link on a previous EPOD to an Atmospheric Optics page and The Atmospheric Phenomenon page eventually solved the mystery. This phenomenon is rarely viewed due to the elevation of the observer. Sub-suns are produced by sun light reflecting off the top surface of flat plate-like snow crystals where as the sub-parhelia occur when sunlight is refracted through the same type of crystals.

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