It was a cold day for Tucson. A big winter storm passed through leaving the mountains coated in snow and daytime temperatures only in the 40's. Late in the afternoon, I noticed the sky had started clearing and decided to try sunset pictures. I am glad I did.
There were some low clouds in the area so I wasn't quite sure what I would get. I would not see the Sun behind the mountains. Let me show you a wide view of what I was dealing with.
Under such circumstances, prospects for a green flash are usually not seem as too good. Let's zoom in at the top of the Sun.
Yep, I caught a rare cloud-top green flash. I saw it as well as captured it with a camera. Not the brightest green flash I had ever seen, but not difficult to see either. I kept shooting and got a bonus a couple of shots later.
Lookey there...it turned blue! I did not see the blue visibly but got the picture. A cloud top blue flash!Blue flashes are more rare since Earth's atmosphere scatters blue light more than green light. The blue light is usually scattered too much to see a blue flash. You need a very clear atmosphere with very few pollutants (both natural and human caused) to get a blue flash. Sometimes a nice storm system is just the ticket to clear things out enough to get that elusive blue flash.
Reprinted with permission from the Half-Astrophysicist Blog.