Flashy Sunday

A BLUE-GREEN FLASH: We’ve all heard of the green flash, the fleeting pulse of emerald light that sometimes appears just above the setting sun. But have you ever heard of the blue-green flash? Thom Peck photographed one from Poway, California, on July 25th:

Atmospheric optics expert Les Cowley analyzed this flash and found elements of blue mixed with the usual green–“in about equal measure,” he says. “This is a rare cloud-top flash.”

It turns out, blue flashes are a thing. They’re formed in the same way as green flashes: a mirage magnifies tiny differences in the atmospheric refraction of red, green and blue light. Blue flashes are generally harder to see than green flashes, because blue is strongly scattered by intervening air and small dust particles.

When Peck was watching the sun set on July 25th, however, conditions favored both colors. The clouds in Peck’s photo were trapped in a marine temperature inversion layer. “Strong temperature gradients produced a strong mirage with well separated colors,” explains Cowley. “And a very clean atmosphere allowed the blue to pass unscattered.”


About Den

Always in search of interesting things to post. Armed with knowledge and dangerous with the ladies.
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10 Responses to Flashy Sunday

  1. Micki says:

    Regarding the grasshopper warning to Jim…

    One year, when we lived in Austin, there was a cicada invasion, that apparently is a periodic phenomena — it was DISGUSTING! Swarms were everywhere! But, in overwhelming abundance swarming around street and parking lot lights. Impossible to walk into a grocery store without stepping on their carcasses, or crunching some to death that didn’t have the wherewithal to get out of the way. I didn’t venture out … too freakin’ creepy!

    The relentless sound was creepy too.
    [audio src="http://www.magicicada.org/about/magi_sounds/m_scassini_chor.mp3" /]


  2. Den says:

    102F, 38.8C outside here. But it’s a dry heat 15% Humidity.

    Inside is 80F, tolerable.


  3. Micki says:

    So what’s the “consensus” gonna be…:?

    “It’s foolish to pretend that the problems in this country are the result of one aberrant presidency,” said Zach Simonson, the Democratic chairman in Wapello County in southeast Iowa. “Trump was the inevitable result of an economic system where both parties put the needs of wealthy donors ahead of working people. ”


  4. Den says:

    Corporate control is evident, Citizens vs United ensured it would continue unabated.


  5. David B. Benson says:

    Meteor display tonite.


  6. David B. Benson says:

    A flock startled out of a tree; another from the trailway. Several more downtown, maybe waiting for leftover pizza. Due to a small detour, 32 minutes to the Old Post Office for a quail dinner.


  7. Den says:

    Still 91F here.


  8. Den says:

    Tomorrows forecast:


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