An Etruscan Vase Moon Rising (APOD 2009 February 23)
Posted: Mon Feb 23, 2009 1:31 pm
Lava lamp: http://apod.nasa.gov/apod/ap090223.html
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Sax Rohmer » The Return of Dr. Fu-Manchu » Chapter XV. Bewitchment
...resolutely fixing my attention upon a tall Etruscan vase in the corner of the window, near to the shop door. Was I losing my senses indeed? A doubt of my own sanity momentarily possessed me. For, struggle as I would to dispel the illusion--there, looking out at me over that ancient piece of pottery, was the bewitching face of the slave-girl! Probably I was glaring madly, and possibly I attracted the notice of the passers-by; but of this I cannot be certain, for all my attention was centered upon that phantasmal face, with the cloudy hair, slightly parted red lips, and the brilliant dark eyes which looked into mine out of the shadows of the shop.
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http://www.atoptics.co.uk/atoptics/sunmir2.htm
http://www.atoptics.co.uk/atoptics/gf2.htm
http://www.atoptics.co.uk/atoptics/gf1.htm
http://en.wikipedia.org/wiki/Green_flash
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Sax Rohmer » The Return of Dr. Fu-Manchu » Chapter XV. Bewitchment
...resolutely fixing my attention upon a tall Etruscan vase in the corner of the window, near to the shop door. Was I losing my senses indeed? A doubt of my own sanity momentarily possessed me. For, struggle as I would to dispel the illusion--there, looking out at me over that ancient piece of pottery, was the bewitching face of the slave-girl! Probably I was glaring madly, and possibly I attracted the notice of the passers-by; but of this I cannot be certain, for all my attention was centered upon that phantasmal face, with the cloudy hair, slightly parted red lips, and the brilliant dark eyes which looked into mine out of the shadows of the shop.
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http://www.atoptics.co.uk/atoptics/sunmir2.htm
http://www.atoptics.co.uk/atoptics/gf2.htm
http://www.atoptics.co.uk/atoptics/gf1.htm
http://en.wikipedia.org/wiki/Green_flash
http://www.atoptics.co.uk/atoptics/gf15.htm wrote:
<<Some textbooks and most web pages say that the green flash is produced by refraction under ordinary atmospheric conditions. That is not true, if it was then we would see flashes much more often.
A standard stable atmosphere gets cooler with increasing height and the air density falls smoothly and monotonically. The lower and denser portion acts as a giant lens bending rays from the setting sun towards the earth. As a result, the rays appear to be coming from a point higher in the sky and the sun appears to be raised up. Green light is refracted more strongly than red and so different coloured images of the sun become very slightly vertically separated. As the sun sinks it develops a green** upper edge and a red lower one. But the effect is small usually only visible in binoculars - do not ever look without full eye protection, even for an instant. To make a green flash these tiny refraction effects need somehow to be considerably magnified. We need a mirage ...
Why a green edge, why not blue? Why are green flashes green? Blue light is refracted more strongly than green or red and the sun's upper edge might be expected to be rimmed with blue outside a band of green. This rarely happens because so little blue light remains in the rays of the setting sun. Blue light is strongly scattered by air molecules, small dust and aerosol particles out of the direct rays. There is a further effect, traces of ozone absorb the orange light which makes the contrast between the red sun and green flash even more dramatic.>>
