Mad Cow wrote in
:

I took this sunset because the higher clouds had pink-and-green
iridescence. I even took a close-up of it. I never got round to
trying to find out what caused it.




Great catch.. seen them, just never had a camera with me at the time.


"High-Level Clouds
High-level clouds form above 20,000 feet (6,000 meters) and since the
temperatures are so cold at such high elevations, these clouds are
primarily composed of ice crystals. High-level clouds are typically thin
and white in appearance, but can appear in a magnificent array of colors
when the sun is low on the horizon."


REF:
http://ww2010.atmos.uiuc.edu/(Gh)/gu...dtyp/home.rxml