Contrails and Halo

November 26, 2005

Phenomenoniii

Provided and copyright by: Thomas Herrmann
Summary authors & editors: Jim Foster; Thomas Herrmann

The photo above showing an array of jet condensation trails, their shadows and portions of the 22 degree halo was taken from Erlensee, Germany on August 27, 2005. Like cirrus type clouds, condensation trails (contrails) are composed of ice crystals, and if enough moisture is available at mid and high altitudes in the troposphere, these jet streaks may stretch across much of the sky. From a given ground location, contrails often occur in similar places overhead since city to city airline routes are generally fixed. Note the upper and lower portion of the 22 degree halo (around the Sun), caused by the presence of more or less randomly oriented, pencil shaped ice crystals. Always use utmost care in looking toward the Sun with binoculars, a telescope, a camera or, of course, your unaided eye.

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