The Half-Astrophysicist Blog

Year End Sunset

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.


December 31, 2010 - Posted by | Astrophotography, Atmospheric Physics, Green Flash


  1. Greetings.. Happy New Year to One & All

    Salutation of Thankfulness for `2010
    Celebration in Gratefulness to `2011.


    Charanjeet Singh Lmaba
    (astral`scientist : gnosiologist)

    Comment by Charanjeet Singh Lamba | January 1, 2011 | Reply

  2. …As the sun slips below the horizon the top edge of it briefly flashes green. You quickly look at your drink – you dont remember ordering absinthe – but rest assured the chances are you have been lucky enough to see the elusive green flash…What causes it?..As light passes from the vacuum of space into the atmosphere which acts like a prism it slows down by 0.03 said I have looked for it during quite a few sunsets but have only seen it once!

    Comment by Naomi Z. Sanders | January 18, 2011 | Reply

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