Corona, Iridescence, Contrail, and Distrail
May 20, 2005
Provided and copyright by: Reinhard Nitze
Summary authors & editors: Jim Foster; Reinhard Nitze
The above photo showing several different optical effects was captured late in the afternoon of April 21, 2004, over Barsinghausen, in northern Germany. On the main picture, the Sun, though partially hidden behind a street sign, is encircled by a corona and iridescent clouds (detached coronae). On the close up view at left , a contrail and its shadow cut across the altocumulus cloud deck. On the close up at right, a second less obvious contrail and its counterpart, a dissipation trail (distrail), can be identified (click on photo for an enlarged view). These associated linear features are nearly perpendicular to the brighter contrail. Whereas contrails require very cold temperatures, at least -40 C, to form, distrails can form in relatively warm, low or middle clouds consisting of water droplets. The heat of combustion of jet aircraft fuel, released into the path swept by the jet, may actually evaporate clouds as long as they aren't too dense. Note the beautiful pastel colors of the iridescent clouds in the close ups.
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