APOD: Sun Halo over Sweden (2018 Jan 01)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 3212
Joined: Fri Dec 04, 2009 3:27 am

APOD: Sun Halo over Sweden (2018 Jan 01)

Post by APOD Robot » Mon Jan 01, 2018 5:05 am

[img]https://apod.nasa.gov/apod/calendar/S_180101.jpg[/img] Sun Halo over Sweden

Explanation: What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a giant lens. In the featured video, however, there are actually millions of tiny lenses: ice crystals. Water may freeze in the atmosphere into small, flat, six-sided, ice crystals. As these crystals flutter to the ground, much time is spent with their faces flat and parallel to the ground. An observer may find themselves in the same plane as many of the falling ice crystals near sunrise or sunset. During this alignment, each crystal can act like a miniature lens, refracting sunlight into our view and creating phenomena like parhelia, the technical term for sundogs. The featured video was taken a month ago on the side of a ski hill at the Vemdalen Ski Resort near Stockholm, Sweden. Visible in the center is the most direct image of the Sun, while two bright sundogs glow prominently from both the left and the right. Also visible is the bright 22 degree halo -- as well as the rarer and much fainter 46 degree halo -- also created by sunlight reflecting off of atmospheric ice crystals.

<< Previous APOD This Day in APOD Next APOD >>
[/b]

ta152h0
Schooled
Posts: 1322
Joined: Mon Aug 29, 2005 12:46 am
Location: Auburn, Washington, USA

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by ta152h0 » Mon Jan 01, 2018 5:35 am

And a Happy New 2018 Year to this comunity and many Halos to come
Wolf Kotenberg

Boomer12k
:---[===] *
Posts: 2243
Joined: Sun Apr 22, 2007 12:07 am

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by Boomer12k » Mon Jan 01, 2018 8:16 am

WOW, that was a spectacular one!!!!

Happy New Year, Everyone!!
:---[===] *

heehaw

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by heehaw » Mon Jan 01, 2018 12:31 pm

Oooohhh! I'm off to Aspen in February!

User avatar
Chris Peterson
Abominable Snowman
Posts: 13805
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by Chris Peterson » Mon Jan 01, 2018 4:17 pm

APOD Robot wrote:An observer may find themselves in the same plane as many of the falling ice crystals near sunrise or sunset.
At the beginning of December in Vemdalen, the Sun never gets more than 5° above the horizon. It's basically always near sunrise or sunset (for the whole four hours the Sun is above the horizon at all).
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

BDanielMayfield
Don't bring me down
Posts: 1646
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by BDanielMayfield » Mon Jan 01, 2018 5:10 pm

Chris Peterson wrote:
APOD Robot wrote:An observer may find themselves in the same plane as many of the falling ice crystals near sunrise or sunset.
At the beginning of December in Vemdalen, the Sun never gets more than 5° above the horizon. It's basically always near sunrise or sunset (for the whole four hours the Sun is above the horizon at all).
We now live just below 44 degrees North, but in the upper Snake River Plain near Henry's Fork of the Snake River. (Great place to see bald eagle, btw) Would it be more likely to see sun dogs up in the mountains, or does elevation matter (we're just below 5000 ft.)

Bruce
"Happy are the peaceable ... "

User avatar
Chris Peterson
Abominable Snowman
Posts: 13805
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by Chris Peterson » Mon Jan 01, 2018 5:18 pm

BDanielMayfield wrote:
Chris Peterson wrote:
APOD Robot wrote:An observer may find themselves in the same plane as many of the falling ice crystals near sunrise or sunset.
At the beginning of December in Vemdalen, the Sun never gets more than 5° above the horizon. It's basically always near sunrise or sunset (for the whole four hours the Sun is above the horizon at all).
We now live just below 44 degrees North, but in the upper Snake River Plain near Henry's Fork of the Snake River. (Great place to see bald eagle, btw) Would it be more likely to see sun dogs up in the mountains, or does elevation matter (we're just below 5000 ft.)
Elevation itself doesn't matter. But temperature does, and if you are at a higher elevation, you may have colder air near the ground (and often times, these ice crystals aren't very high).
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
RJN
Baffled Boffin
Posts: 1440
Joined: Sat Jul 24, 2004 1:58 pm
Location: Michigan Tech

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by RJN » Mon Jan 01, 2018 6:56 pm

At 480 kilometers distance, an emailer pointed out that Vemdalen is not really very "near" Stockholm. I therefore tweaked the NASA APOD's text to now say that the ski resort is in "central Sweden". We apologize for the oversight.

- RJN

BDanielMayfield
Don't bring me down
Posts: 1646
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by BDanielMayfield » Mon Jan 01, 2018 7:21 pm

Chris Peterson wrote:
BDanielMayfield wrote:
Chris Peterson wrote: At the beginning of December in Vemdalen, the Sun never gets more than 5° above the horizon. It's basically always near sunrise or sunset (for the whole four hours the Sun is above the horizon at all).
We now live just below 44 degrees North, but in the upper Snake River Plain near Henry's Fork of the Snake River. (Great place to see bald eagle, btw) Would it be more likely to see sun dogs up in the mountains, or does elevation matter (we're just below 5000 ft.)
Elevation itself doesn't matter. But temperature does, and if you are at a higher elevation, you may have colder air near the ground (and often times, these ice crystals aren't very high).
Good, as it is certainly cold enough here as it is in the single digits most nights and seldom gets above freezing now. We're learning to view the 30's as warm, like the locals.
"Happy are the peaceable ... "

User avatar
bystander
Apathetic Retiree
Posts: 17104
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by bystander » Mon Jan 01, 2018 7:21 pm

RJN wrote:At 480 kilometers distance, an emailer pointed out that Vemdalen is not really very "near" Stockholm.
In astronomical terms, it's very close. :mrgreen:
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

BDanielMayfield
Don't bring me down
Posts: 1646
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: East Idaho

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by BDanielMayfield » Mon Jan 01, 2018 7:49 pm

bystander wrote:
RJN wrote:At 480 kilometers distance, an emailer pointed out that Vemdalen is not really very "near" Stockholm.
In astronomical terms, it's very close. :mrgreen:
That is very funny bystander.
"Happy are the peaceable ... "

User avatar
Chris Peterson
Abominable Snowman
Posts: 13805
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Sun Halo over Sweden (2018 Jan 01)

Post by Chris Peterson » Tue Jan 02, 2018 12:37 am

bystander wrote:
RJN wrote:At 480 kilometers distance, an emailer pointed out that Vemdalen is not really very "near" Stockholm.
In astronomical terms, it's very close. :mrgreen:
Indeed. A mere 5 x 10-11 light years.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com