A Feather in the Sky

March 05, 2009


Photographer: Christine Churchill
Summary Author: Jim Foster, Christine Churchill

The photo above showing feathery cirrus clouds in an azure blue sky was captured over Northern California on October 8, 2008. Cirriform clouds are found at altitudes generally above about 20,000 ft (6,000 m) and are predominantly composed of small hexagonal ice crystals. Because these crystals are widely dispersed (winds are stronger in the upper atmosphere than they are near the surface), cirrus type clouds take on a fibrous appearance, and they tend to point in the direction the upper air winds are blowing. When cirrus clouds streak the sky, the weather beneath them is fair much more often than not.

Photo details: Sony A 100 camera; F-22, 60 mm lens; ISO 200; with a polarizing filter.