Some Natural Spectroscopy!

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p_zetner
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Some Natural Spectroscopy!

Post by p_zetner » Mon Jan 15, 2018 8:08 pm

The weather here has been quite frigid lately with high temperatures near -20C. Low temperatures and low Sun definitely curtail imaging and observing but, on the plus side, we are occasionally treated to beautiful displays of atmospheric phenomena involving atmospheric ice crystals. Today, we could witness a day-long spectacle of complex arcs associated with refraction (and consequent dispersion) through these ice crystals. Here are two photos of the beauty on display.
IMG_2685_proc.png
IMG_2685_proc.png (672.7 KiB) Viewed 982 times
IMG_2687_proc.png
IMG_2687_proc.png (594.67 KiB) Viewed 982 times

It's actually quite hard to appreciate the extent over the sky of the various arcs and halos from photographs alone. The inner circular halo has an angular radius of 22 degrees while the outer "halo" (actually a big arc - the supralateral arc) has a 46 degree radius. That's a lot of sky coverage and is very impressive to witness by eye! I was limited to a 24mmf camera lens for these pics and the cold killed my battery before I could start setting up a panorama.

Here are the names of some of the observed features:
IMG_2687_proc_lbls.png
IMG_2687_proc_lbls.png (185.57 KiB) Viewed 983 times
There is a reasonably good description of these at http://www.atoptics.co.uk/ under the topic "Ice Halos".

All of the observed features can be explained by the phenomenon of "minimum deviation" of a light ray propagating through a prism (hexagonal prism in the case of these ice crystals). Arranging the minimum deviation condition can be a useful technique in prism spectroscopy.

Cheers.
Peter.

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Re: Some Natural Spectroscopy!

Post by marktownley » Mon Jan 15, 2018 11:20 pm

Fantastic! I'm always looking up for atmospheric optics, fascinating to see.
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Re: Some Natural Spectroscopy!

Post by Montana » Tue Jan 16, 2018 12:53 pm

Wow! these are absolutely superb, I bet in really life they were amazing. I have never seen anything other than classic sundogs.

:hamster: :bow
Alexandra

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Re: Some Natural Spectroscopy!

Post by rsfoto » Tue Jan 16, 2018 7:31 pm

Hi,

Absolutely stunning. Once in a lifetime event ...
regards Rainer

Observatorio Real de 14 San Luis Potosi Mexico

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Re: Some Natural Spectroscopy!

Post by highfnum » Tue Jan 23, 2018 12:40 am

a real nice catch

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Re: Some Natural Spectroscopy!

Post by Carbon60 » Tue Jan 23, 2018 8:30 pm

Beautifully captured, Peter. What a treat.

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Re: Some Natural Spectroscopy!

Post by Wah » Wed Jan 24, 2018 4:07 am

I can see the Ha line!
Just kidding :P

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Re: Some Natural Spectroscopy!

Post by p_zetner » Wed Jan 24, 2018 6:13 pm

Thanks everyone.

I wish I’d had the foresight to charge my camera battery fully and put together a mosaic. It was quite the spectacle.

Cheers.
Peter.

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Re: Some Natural Spectroscopy!

Post by christian viladrich » Fri Jan 26, 2018 7:27 pm

Hello Peter,
This is beautifull. Thanks for sharing. I have never had such a spectacle here.
Christian Viladrich
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Re: Some Natural Spectroscopy!

Post by highfnum » Sat Feb 03, 2018 12:25 pm

:D 3 dog sun
Does this mean another
War of the roses?

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