Parhelia and Contrails

May 19, 2004


Provided and copyright by: Thierry Demange
Summary authors & editors: Jim Foster; Thierry Demange

The photo of the eye-catching parhelia above was taken near Col de la Schlucht, France (Vosges province) on January 30. 2004. This particular parhelia (also referred to as a sundog) remained a companion to the Sun for more than 2 hours! Evidently the multitudinous contrails as well as the presence of thin cirrus clouds contributed to the longevity of this bright sundog -- a near continuous supply of ice crystals was provided. When moisture levels in the upper troposphere are sufficient, vapor trails from the exhaust of jet aircraft (commercial flights) can at times practically cover the sky. The most recent contrails are sharper and narrower. Notice also a portion of a 22 degree halo just below the parhelia, indicating that some of the ice crystals favor random orientations.

Photo details: Canon EOS 10D + zoom, 28-135mm, at 100 ISO.

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