APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

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APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by APOD Robot » Sun Dec 28, 2014 5:07 am

Image Unusual Light Pillars over Latvia

Explanation: What's happening over that town? Close inspection shows these strange columns of light occur over bright lights, and so likely are light pillars that involve falling ice crystals reflecting back these lights. The above image and several similar images were taken with a standard digital camera in Sigulda, Latvia in late 2009. The reason why these pillars fan out at the top, however, remains a topic for speculation. The air was noted to be quite cold and indeed filled with small ice crystals, just the type known to create several awe-inspiring but well known sky phenomena such as light pillars, sun pillars, sun dogs, and moon halos. The cold and snowy winter occurring this year in parts of Earth's northern hemisphere is giving sky enthusiasts new and typically unexpected opportunities to see several of these unusual optical atmospheric phenomena for themselves.

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Ann » Sun Dec 28, 2014 6:04 am

When you see pillars like these, you know it's cold outside. :wink:

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Ron-Astro Pharmacist » Sun Dec 28, 2014 6:23 am

:ssmile: :ssmile:
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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by geckzilla » Sun Dec 28, 2014 6:23 am

That song always gave me major creep vibes.
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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Ron-Astro Pharmacist » Sun Dec 28, 2014 7:03 am

I think the conical shapes involve some sort of an atmospheric gradient that gradually fans out to encompass the entire circumference of the light source.
Light pillars 2.jpg
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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by BennyH » Sun Dec 28, 2014 1:29 pm

Could it be that it is just raining at a heigher point, and the light is only focused through the icefall?

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Mr_Ed » Sun Dec 28, 2014 1:49 pm

Perhaps the light fixture lens has a focusing effect, and the light column width changes as the beam goes in and out of focus...

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by BennyH » Sun Dec 28, 2014 2:03 pm

I guess... these are streetlights that are actually focused downwards, so the lightbeam must be created by the form of the icecrystals themselves

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by bystander » Sun Dec 28, 2014 2:47 pm

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Chris Peterson » Sun Dec 28, 2014 3:05 pm

Ron-Astro Pharmacist wrote:I think the conical shapes involve some sort of an atmospheric gradient that gradually fans out to encompass the entire circumference of the light source.
Something to keep in mind... and this applies to a number of other posts, as well: the light pillars are not physically above the light fixtures. Like all light pillar phenomena, we are seeing some type of reflection or refraction from ice or water droplets between us and the light source. The pillars are not physical, but are virtual images, created in a different position for every viewer (like a rainbow is). Get close enough to the light fixture and the effect would disappear.
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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Les Cowley » Sun Dec 28, 2014 5:04 pm

The explanation for these unusual pillars was posted on OPOD ( http://www.atoptics.co.uk/opod.htm ) some time ago. See this http://www.atoptics.co.uk/fz193.htm page. They are produced by columnar hexagonal ice crystals drifting with their long axes horizontal.

More of these pillars at -http://www.atoptics.co.uk/fz179.htm

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Ron-Astro Pharmacist » Sun Dec 28, 2014 5:56 pm

Chris Peterson wrote:
Ron-Astro Pharmacist wrote:I think the conical shapes involve some sort of an atmospheric gradient that gradually fans out to encompass the entire circumference of the light source.
Something to keep in mind... and this applies to a number of other posts, as well: the light pillars are not physically above the light fixtures. Like all light pillar phenomena, we are seeing some type of reflection or refraction from ice or water droplets between us and the light source. The pillars are not physical, but are virtual images, created in a different position for every viewer (like a rainbow is). Get close enough to the light fixture and the effect would disappear.
I was noticing the base lights and it seemed wider in orange light pillar and in the example I found. We don’t see the blue light base in the APOD today so I can’t tell it may be larger too. Just a thought?

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by geckzilla » Sun Dec 28, 2014 6:44 pm

Les Cowley wrote:The explanation for these unusual pillars was posted on OPOD ( http://www.atoptics.co.uk/opod.htm ) some time ago. See this http://www.atoptics.co.uk/fz193.htm page. They are produced by columnar hexagonal ice crystals drifting with their long axes horizontal.

More of these pillars at -http://www.atoptics.co.uk/fz179.htm

Les Cowley (http://www.atoptics.co.uk)
Thanks for posting this, Les. I was playing with HaloSim for a couple of hours trying to figure this out. I had the horizontal columns down but couldn't quite get all the numbers right. Who knows how much more time I would have wasted? Someone else already did it!
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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by alter-ego » Mon Dec 29, 2014 5:28 am

geckzilla wrote:
Les Cowley wrote:The explanation for these unusual pillars was posted on OPOD ( http://www.atoptics.co.uk/opod.htm ) some time ago. See this http://www.atoptics.co.uk/fz193.htm page. They are produced by columnar hexagonal ice crystals drifting with their long axes horizontal.

More of these pillars at -http://www.atoptics.co.uk/fz179.htm

Les Cowley (http://www.atoptics.co.uk)
Thanks for posting this, Les. I was playing with HaloSim for a couple of hours trying to figure this out. I had the horizontal columns down but couldn't quite get all the numbers right. Who knows how much more time I would have wasted? Someone else already did it!
Yup. That was a fun one. I wasn't sure if that hypothesis still held up but I guess it does. What a nice surprise for Les to post here. :D
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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by DavidLeodis » Mon Dec 29, 2014 10:30 pm

I think the "2009" in the image was taken "in late 2009" in the explanation is wrong as the image was the topic of the APOD of January 12 2009. The “above image and several similar images” in the explanation to the APOD of December 28 2014 is a link to a webpage in the SpaceWeather website that presumably has/had this image (and others) but that webpage only had text when I saw it today (December 29 2014). In the text it did however state “Aigar Truhin. Image taken: Dec. 28, 2008. Location: Sigulda, Latvia" so it presumably would have been the same image as today's APOD. :?

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Re: APOD: Unusual Light Pillars over Latvia (2014 Dec 28)

Post by Donald Wayne Stoner » Thu Jan 08, 2015 8:12 pm

I spent sone time playing with this one the last time it came up; I also made a webpage out of it:
http://www.dstoner.net/Math_Science/Pillars.html