Sunday, January 3, 2010

Circumzenithal arc, again

Jet contrails are thought to suppress the diurnal temperature change by about 1 degree C. This morning, the conditions were right to maximize this influence, for it would have been a cloudless morning except for the contrails from jets to and from Los Angeles. The photo on the left shows a contrail becoming feathered. The sky was full of these feathered contrails that when they drifted overhead would create the arc shown above. My observation is that contrails make poorer arcs. The fluffiness of contrail-induced cirrus clouds reduce the clarity of the bands of color.


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