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Sundog

Posted by Conservators on Apr 2, 2012 5:09:44 AM

Author: Georgina

Date: 28/03/12
Temperature: -23c
Wind Speed: 25 kts
Temp with wind chill: -38c
Sunrise: 8:39am
Sunset 7:15pm

 

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Sundog seen from Scott Base (photo by G. Evans, AHT)

 

For the past few weeks, we have been enjoying the rising and setting of the sun in something approaching normal daylight hours.  On Monday we were able to see a sundog, (scientific name: parhelion); a very special atmospheric phenomenon in which bright spots of light appear in the sky on either side of the sun.


Sundogs are created by ice crystals in the air which act as light-bending prisms. When randomly orientated, a complete halo or luminous ring around the sun is created, but at lower levels the crystals (sometimes called diamond dust) become vertically aligned, causing the light to be refracted horizontally.

 

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Detail (photo by G. Evans, AHT)

The spots we saw were like partial blurred rainbows, with the red side innermost. I didn’t get the chance to see one of these when I was last here in 2010, so I feel very lucky indeed to have seen one now.  Sundogs (also known as mock or phantom suns) can be seen anywhere in the world, but rarely as obvious or as bright as when the sun is low on the horizon and in very cold regions like Antarctica.

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