# weird light phenonenom **URL:** \ **Category:** Factual Questions\ **Created:** [January 23, 2012, 8:22pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427 "2012-01-23T20:22:06Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![hilltopper](https://avatars.discourse-cdn.com/v4/letter/h/c68b51/32.png) [@hilltopper](https://boards.straightdope.com/u/hilltopper)\ **Post date:** [January 23, 2012, 8:22pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/1 "2012-01-23T20:22:06Z")
Can anyone explain this? I was skiing in Whistler, Canada and had to pull out my Go-Pro helmet camera when I saw this weird glowing column of bright sparkling light. From where I was standing it looked like a fountain of light. SUPER bright. As I skied closer to it and around the corner it shrunk to more of a hovering ball of light. The sparkling became more apparent. As I skied around it the concentration of light seemed to stay fixed in place, hovering above the earth. however, as I got closer and further around the corner it continued to diminish in size until it finally disappeared when I got into the shade. I have skied my whole life, grew up in a cold and snowy climate and have never seen anything like this. Can anyone tell what this phenomenon is called and how it works? Here is a link to the video. I just posted it to YouTube so I could learn more about it. Please ignore the bad skiing, and forgive the bad camera work. [![]( " - YouTube") ](https://www.youtube.com/watch?v=9-Gmqugx9Mk) ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [January 23, 2012, 8:43pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/2 "2012-01-23T20:43:31Z")
It’s just the snow mirroring the sunlight. Like [this](http://www.maremmaguide.com/image-files/ocean_sunsets3afrocheye.jpg), but on snow. ---
**Author:** ![Blakeyrat](https://avatars.discourse-cdn.com/v4/letter/b/ecd19e/32.png) [@Blakeyrat](https://boards.straightdope.com/u/Blakeyrat)\ **Post date:** [January 23, 2012, 8:48pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/3 "2012-01-23T20:48:13Z")
I’m not going to watch 6.5 minutes of home movies to see what you’re talking about. Can you either link directly to the relevant portion of the movie, or edit it down? Unless the column of light is in the first 10 seconds; in which case, it’s just the sun reflecting off the snow AFAICT. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [January 23, 2012, 10:29pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/4 "2012-01-23T22:29:26Z")
Yeh, it looks like some kind of lensing of sunlight, probably from the snow/ice crystals in the air. Certainly odd though, I can’t tell from this video, since there’s no true perception of depth, if it’s projected on the side of that hill, of did it look like it was just a shaft of bright light in the middle of the air? ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [January 23, 2012, 11:07pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/5 "2012-01-23T23:07:03Z")
I don’t see how it can be sunlight reflecting off the snow, like in **Chessic Sense** ’s picture. The snow is in shadow. I’d have to guess that the snow on the hill has a crystal shape that causes it to act as a retro-reflector over a small range of angles. If I’m right, the portion of the snow where you’re seeing the light is reflecting the light of the snow near you into your eyes. Similar to the way road signs reflect headlights preferentially back towards the driver. ---
**Author:** ![Dickerman](https://avatars.discourse-cdn.com/v4/letter/d/8baadc/32.png) [@Dickerman](https://boards.straightdope.com/u/Dickerman)\ **Post date:** [January 23, 2012, 11:36pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/6 "2012-01-23T23:36:20Z")
I think the guy who commented on YouTube got it right when he said it is known as a subsun. It looks the same as what’s shown here: [Subsun](http://www.atoptics.co.uk/fz120.htm) ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [January 23, 2012, 11:37pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/7 "2012-01-23T23:37:13Z")
I’m surprised that you didn’t synch the video to _Also Sprach Zarathrusta_. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 24, 2012, 12:06am UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/8 "2012-01-24T00:06:52Z")
It appears to be a **Sun Pillar** , which is caused by sunlight reflecting from flat (usually hexagonal) plates that are oriented very nearly flat relative to the ground. The lack of color separation shows that this is not a refractive phenomenon, and it is clearly in perfect alignment with the sun, as you can tell from the shados of people around it. Sun Pillars usually appear _above_ the sun, but can appear below the horizon, especially if you’re in an elevated area (for instance, on a plane). I’ve seen them plenty of times. [http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/ice/sp.rxml](http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/opt/ice/sp.rxml) > **[Light pillar](https://en.wikipedia.org/wiki/Light_pillar)** > > A light pillar is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source. The effect is created by the reflection of light from tiny ice crystals that are suspended in the atmosphere or that comprise high-altitude clouds (e.g. cirrostratus or cirrus clouds). If the light comes from the Sun (usually when it is near or even below the horizon), the phenomenon is called a sun pillar or solar pillar. Light pillars can also be caused b Si... ---
**Author:** ![hilltopper](https://avatars.discourse-cdn.com/v4/letter/h/c68b51/32.png) [@hilltopper](https://boards.straightdope.com/u/hilltopper)\ **Post date:** [January 24, 2012, 3:38am UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/9 "2012-01-24T03:38:14Z")
Yes, I concur it must be a Subsun. Was very interesting to see in person. Apparently, they are usually seen from an airplane. They are like many of you described formed by a collection of micro ice crystals in the air and the sun. They are better described here: [http://www.atoptics.co.uk/fz120.htm](http://www.atoptics.co.uk/fz120.htm) (same link as Dickerman) and here: [Subsun - Wikipedia](http://en.wikipedia.org/wiki/Subsun) There are a few more photographs as well. From the source: > [@](#): > > The subsun can often be seen from an airplane as a blinding and shimmering disk or oval. Look down on sunward side of the aircraft at clouds or mist to see it drifting with the 'plane over the clouds or landscape. > > The subsun is an ice halo formed by reflection of sunlight from the upper and lower nearly horizontal faces of plate crystals. The crystals act as millions of tiny mirrors to form a reflected image of the sun. When the crystals have larger wobbles from horizontal the subsun becomes a lower sun pillar. Thank you for your interest ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [January 24, 2012, 6:36am UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/10 "2012-01-24T06:36:38Z")
'Course, aliens haven’t been ruled out. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 24, 2012, 12:32pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/11 "2012-01-24T12:32:27Z")
> [@](#): > > Yes, I concur it must be a Subsun. Was very interesting to see in person. Not really a _subsun_. A Subsun is what you get when the ice plates are _really_ horizontal, and act very much like a mirror, reflecting the image of the sun. In that case, you get pretty close to a disc, as far below the horizon as the sun is above it. I’ve seen these from airplanes. This appears to be spread out over a horizontal region. It occurs when the plates have a range of angles, but are relatively horizontal. You expect this sort of thing closer to the ground, where the air’s more turbulent. Then you get a vertical shaft of light, rather than a confined image. Of course, you don’t generally get a perfect image of the sun.. There are lots of stages betweebn a sunsun and an inferior solar pillar, but I think you’re closer to the latter here. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [January 24, 2012, 1:31pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/12 "2012-01-24T13:31:03Z")
> [@Blakeyrat](#): > > I’m not going to watch 6.5 minutes of home movies to see what you’re talking about. > > Can you either link directly to the relevant portion of the movie, or edit it down? > > Unless the column of light is in the first 10 seconds; in which case, it’s just the sun reflecting off the snow AFAICT. Then why waste your time to post at all? ---
**Author:** ![Sigene](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Sigene](https://boards.straightdope.com/u/Sigene)\ **Post date:** [January 24, 2012, 3:27pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/13 "2012-01-24T15:27:20Z")
But it is clear to me that the sunlit slope in front of the shaded hillside is acting like a parabolic mirror reflecting the sunlight back onto the shaded hill. THis is even more evident by the footage where glittery snow in air is seen around 4 min. The skier is in the spot of the mountain that is doing the reflecting and is in essence standing in (or close to) the mirror. I don’t think it is a subsun because it looks like subsuns reflect light back up to airplanes and are caused by snowflakes in the air. I think this caused by a snow covered concave hillside reflecting and concentrating the light. ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [January 24, 2012, 5:25pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/14 "2012-01-24T17:25:11Z")
> [@Sigene](#): > > But it is clear to me that the sunlit slope in front of the shaded hillside is acting like a parabolic mirror reflecting the sunlight back onto the shaded hill… I had the same thought, that the bowl-shaped valley was acting as a parabolic mirror, focusing the sunlight into a shaft, reflecting off the ice crystals in the air. There’s not a lot, but I think I do see a bit of refraction going on, in that one side of the shaft is slightly warmer in color, and the other side slightly bluer. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 24, 2012, 5:44pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/15 "2012-01-24T17:44:59Z")
Sorry, folks. The odds of a valley (especiallyu one coated with diffusely reflecting snow) acting like a parabolic reflector is effectively zip. And Naturally-occurring lenses and mirrors tend to concentrate light into cusp-shaped regions called _caustic_, with generally different shapes than the simple column you see in the film. That’s a solar pillar. See the links in my post. ---
**Author:** ![hilltopper](https://avatars.discourse-cdn.com/v4/letter/h/c68b51/32.png) [@hilltopper](https://boards.straightdope.com/u/hilltopper)\ **Post date:** [January 24, 2012, 8:48pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/16 "2012-01-24T20:48:32Z")
Another link that seems to show very similar pictures that support the SubSun theory: [OPOD - Greenland subsun](http://www.atoptics.co.uk/fz556.htm) ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [January 25, 2012, 2:46pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/17 "2012-01-25T14:46:20Z")
> [@CalMeacham](#): > > Sorry, folks. The odds of a valley (especiallyu one coated with diffusely reflecting snow) acting like a parabolic reflector is effectively zip. I don’t believe you. I realize you’re asserting that something _isn’t_ possible, but I’ll say it anyway: Cite? ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 25, 2012, 4:02pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/18 "2012-01-25T16:02:17Z")
Take a look sometime at how optics are manufactured, and the tolerances used. If you’ve got a shiny suirface reflecting the light, I could see your getting caustics and relatively good foci. In fact, it’s happened with buildings in Los Angeles (The Gehry-designed, very shiny Disney auditorium [Walt Disney Concert Hall - Wikipedia](http://en.wikipedia.org/wiki/Walt_Disney_Concert_Hall) ) and the Las Vegas Vdara Hotel, which is notorious for its “Death Ray” > **[Vegas Hotel Pool 'Death Ray' Burns Tourists](https://abcnews.go.com/Travel/las-vegas-hotel-pool-sunlight-swimming-tourists/story?id=11739234)** > > Forget sunscreen. At one Las Vegas pool, you might want to consider full-body armor to protect you from the sun's powerful rays. Guests at the new Vdara hotel have been complaining that because of an architectural flaw on the glass skyscraper, the... > **[Las Vegas News | Breaking News & Headlines | Las Vegas Review-Journal](https://www.reviewjournal.com)** > > The Las Vegas Review-Journal is Nevada's most trusted source for local news, Las Vegas sports, business news, gaming news, entertainment news and more. Note that these are both shiny buildings. As you note, it’s hard to find a “Cite?” for a negative. The very nature of a diffuse reflecting surface – in which light is scattered in all directions – prevents it from concentrating light towards a focus, as happens with parallel light reflecting in a specular (non-diffuse) fashion from a paraboloid. Fortunately, there exists a counterexample – the “umbrellas” used by photographers to provide diffuse light from one direction. They bounce light off a concave diffuse curved surface: [![](https://en.wikipedia.org/wiki/File:SVLightWithFlexReflect.jpg) ](https://en.wikipedia.org/wiki/File:SVLightWithFlexReflect.jpg) It’s not exactly the same thing, since the light source is relatively close (but isn’t a point source, and probably isn’t at the focus), but it illustrates the point. If you doubt it, take a white umbrella out and try to focus the light from a distant source using it. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 25, 2012, 4:35pm UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/19 "2012-01-25T16:35:00Z")
> [@Dickerman](#): > > I think the guy who commented on YouTube got it right when he said it is known as a subsun. It looks the same as what’s shown here: [http://www.atoptics.co.uk/fz120.htm](http://www.atoptics.co.uk/fz120.htm) [Sundogs](http://www.atoptics.co.uk/halo/parhelia.htm) are cool too; plus they’re fun to say. And they really look like the welcoming lights that greet Bowman as he goes Beyond. This is from the same site quoted. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [January 26, 2012, 3:41am UTC](https://boards.straightdope.com/t/weird-light-phenonenom/610427/20 "2012-01-26T03:41:04Z")
Actually, it occurs to me that there IS a case where a diffuse white reflector is used – inside _integrating spheres_. These are perfect spheres that are hollow\* and coated with white diffuse reflecting material. the idea is that you introduce light that you’re curious about in through an aperture. It bounces off the walls many times and gets regularized in the process, so if you stick a detector into the sphere you get a measure of the absolute flux of photons, without “hot spots” (they often put a baffle in to prevent light from going directly from the source to the detector). If the theory that you could use the diffuse interior as a sort of parabolic reflector were true, there ought to be an image of the source on a line connecting the source with the center of the sphere. But there isn’t – the whole point of using the sphere is to see to it that the light is “evened out”. Even if the diffuse coating isn’t perfect, the multiple reflections make the walls of the sphere act like a nearly perfevct Lambertian source. > **[Integrating sphere](https://en.wikipedia.org/wiki/Integrating_sphere)** > > An integrating sphere (also known as an Ulbricht sphere) is an optical component consisting of a hollow spherical cavity with its interior covered with a diffuse white reflective coating, with small holes for entrance and exit ports. Its relevant property is a uniform scattering or diffusing effect. Light rays incident on any point on the inner surface are, by multiple scattering reflections, distributed equally to all other points. The effects of the original direction of light are minimized. ... \*especially with infrared sources, people often fake the “perfect sphere” part. But visible integrating spheres are made nearly perfectly spherical.