APOD: Unusual Light Pillars Over Latvia (2009 Jan 12)

[rrclark]

I'm about 95% sure it's one of two things, both of which have already been
suggested.

We don't really know enough about the image, especially its field of view.
The image appears to be framed by some sort of doorway or window. If the
dark edges are parallel and vertical then it is fairly close to 'standard'.
If the fov is wide enough then the trumpets may be caused by the normal
pillar blending into some other arc generating geometry but without
necessarily a change in crystal population or orientation.

OTOH, even with a fairly wide angle image, this still seems a little close
to be one of the normal halo distances (22 deg etc). In this case (this
was my first thought on seeing the picture) it could be that there is a
change in the wind/turbulence at the top of an inversion. I do get the
impression that the trumpet on the red pillar is slightly 'lower' than
over the blue one. The red light also seems to be slightly more distant
from the camera than the blue light, which would be consistant with
that interpretation.

Well ok, you may have to use averted imagination to see this:-)

[PiTHON]

If we knew the lens and sensor size this picture was taken with, we could begin to deduce the critical angles of reflection and test this hypothesis against other images of pillars. If multiple images from different perspectives all show the fan at the same angular height, than it is entirely an optical-scattering property, and has nothing to do with the height of fog, temperature layers, moisture-ice gradient, or wind layer.

Chad Moore, US National Park Service

Dont forget to read the whole paragraph, guys The APOD picture links to this page: http://spaceweather.com/submissions/lar ... 501854.jpg which has 3 other pictures to help decipher whats happening. "Pictures are taken with Nikon D90, 5sek. exposure @ISO 640-200" Which has a 12.3mp sensor: 23.6 x 15.8 mm CMOS (DX format)

Here is wundergrounds weather history for a town 32 miles away, on Dec 28th (the day the pictures were taken): http://www.wunderground.com/history/air ... atename=NA

In the 3rd picture you can see the dimmer lights produce the same flaring near the top, so on the APOD picture I would say only 2 lights are visibly flared because they are quite a bit brighter and the shot was too bright (also there is only 1 star visible in the whole shot). The other pictures also show a beam of light going straight up through the middle of the flared light, so its really a smooth flare with a normal beam shooting through the center. EDIT: using google i found tihs page: http://www.atoptics.co.uk/opod.htm its interesting because of picture 3, which shows 3 shots of the red pillar taken 30 seconds apart. Within 1 minute it goes from a normal pillar to a pillar with a trumpet on top.

Using stellarium centered in on Sigulda, Latvia, on Dec 28th 2008 it looks like the pictures were taken at around 12 to 12:30am (the bright stars on the 3rd picture, just left of center that are aligned nearly vertical are Deneb and Sadr, Vega is in the lower right). The APOD picture appears to have been taken first, 2~ hours earlier (I think the only visible star is Vega, which moved from the upper left to the lower right of the white pillar in the other pictures).

wunderground shows the wind was blowing south, and the picture was taken facing West Northwest, maybe this is relevant also assuming his town had the same wind conditions; the upper layer of the pillars would be moving right to left, possibly creating ice crystals nudged onto their sides causing the flares, somehow. My guess seems a little simple, maybe you guys can use this extra information to come up with something better

[fox19]

There still a few more pictures to be seen, I don't know if anyone has reviewed them yet, also there is the information of what camera it was taken with. The link is below. I don't know much about pillars and all this. But I did however look up Sigulda the town where the picture was taken and turns out it is a town right beside a river bottom. And accordig to what is said there it sounds like there is many nearby creeks and bodies of water. Which might be another factor in these pillars.


http://spaceweather.com/submissions/lar ... 501854.jpg

[MrsMary]

Hello Everyone: I live in the Canadian province of British Columbia (pretty much right in the middle of the province) and I can tell you that we had this same phenomenon happen here on December 30th (2008). We live outside of the city and as we were driving into town that evening, we saw the same unusual light pillars over our airport and city. I've seen these light pillars here on a few ocassions and I can definitely say that the temperatures were VERY cold each time I've seen them, usually around minus 30 degrees celsius. So I would have to go along with the theory of lights reflecting off falling ice crystals, it just seems logical to me. Just my opinion. Also, I just want to say, I've logged onto APOD's site every day for the past 3 years at least and always thoroughly enjoy the photos featured there, thank you APOD!

[richard]

I worked at the pulpmill in grande praire a couple of winters ago and we would see this all he time when the temperature was below about 14-16 minus. The mill put out a large amount of steam and as you drove into the valley the mill was in you could see the steam rise to certin hight then spread out and fill the area around the mill like a fog bank, all the lights that were open to shine up had light pillars like in this picture. when it got to the top of the layer of fog it would fan out as the crystals of ice formed buy the fog would be thinner . It would 'snow' all day and leave about 1/8 inch of very fine snow on everthing . It was neat to see but I never thought it would be atopic of dicussion on this site or I might have taken pictures.It was quite neat to see. The mill would out of sight in the fog , plumes of steam would rise out of the fog and then settle back down to form the fog that hid the mill, and we would work in this fog all shift then go back up the hill to a clear sky.

[bapcomember]

Since the ice crystals are probably uniformly present in the area. the camera is recording a "fan" of light edge-on.

[David]

Looking at all the pictures the cones seem to all be starting at the same angle from horizontal. If the cones were really there and not just an effect generated from the angle you are looking at them, the farther away cones would start lower in the picture. They do not start lower in any picture. The farthest away ones don't exhibit cones because either the ice layer is close to the ground and/or the light has faded so much they are not visible. A time exposure would show if this is true or not.
I think the simplest answer works here. As I stated before I think it is just an effect generated be the viewing angle of horizontally oriented ice crystals as occur in sun pillars.

[seel01]

It may be illusory, but the bluish column appears to spread at a greater angle than the reddish column. A possible data point...

[Teyssier]

I have seen this light intensity pattern in a simulation I ran several years ago. I was using Tempest, a light propagation simulator, to create a map of the intensity of light as it passed through a diffraction grating (slitted, not reflecting). I was looking at a cross-section of the grating, and observed the same cone and fan shape at the end of the grating slit. This is just the result of the light collimation (cone) and bending (fan) at a sharp edge.

I speculate that this sharp edge is created by a "sharp" density change in the atmosphere. (Many people have suggested that this fan was created by a temperature change, and I am glad to support them.)

What is curious to me is the collimation of the light. I can only speculate further, and say that the collimation of the light is due to the temperature change created by the light in very still air. The lamps emit in the visible wavelength, refracting off ice crystals to create the intensity pattern we see. The lamps also emit in the infrared, heating the air in a vertical column (lowering the density) and creating the exact conditions necessary for the refraction in the visible. Above a certain height, the temperature change created by the light is no longer the dominant effect.

Amazing photograph. Congratulations on this unique capture!

[Revloc10]

First, look at the diagram on this website (http://www.atoptics.co.uk/halo/lpil.htm) and then remember that the image was taken with a digital camera. I suspect that the phenomena is a result of the curve of the lens in the digital camera.

However, the other likely explanation is that the light which originates on the left side of the origin actually converges and crosses the central beam, fanning out on the right side of the column. Similarly, the light that originates on the right side of the source converges and crosses the central beam, fanning out on the top left side of the column.

That's just my two cents.

[guiney72]

To me I see the geometry of spheres. See my attached image. I have drawn a series of arcs over the image that seem to describe more accurately the shape of the phenomenon. I'm not sure why this might happen but I don't see it as conical or as a V. There appears to be a hotspot before the diverging area. This seems to occur where the arcs intersect.

[parkerjh]

As for the noticed (and somewhat measured) cones that are different with color. Scattering and difraction are wavelength (color) dependent processes.

[BMAONE23]

Didn't read through all 4 pages of posts but what if
The ice crystals are acting to "Lase" the photons to a height where the Ice crystals begin to diminish in quantity then the light begins to act normally and spread out again.

[erisca]

Hello
These "pillars" make me think of a gigantic "psf" aka a "point spread function, that is the image of a subresolution sphere made by a microscope. Typically the sphere will be deformed (elongated) along the axis of the microscope (the "Z" axis) so as to take the appearence of a rugby ball or in extreme case when using low Numerical Aperture objectives, it would look just like the bright straight pillar! The expanding lobes at the end of the pillar would in this case correspond to airy disks, ie diffraction patterns that create concentric dark and bright circles (or disks) when one looks down in the microscope.
Now, I am just a microscope user and not a expert in optics, but you can find much more accurate descriptions of microscope image formation out there.
Is it possible that the bright point-like light source on the surface are somehow reflected a few meter above the ground where they are picked up by the ice crystals that are somehow arranged to form some kind of lens?
That or somebody huge is looking at this town in Latvia using a giant microscope.......

Cheers and thanks for the magnificent work to all of you at APOD.
Eric Scarfone, CNRS, KI, STockholm

PS I join examples of PSF that I made using a confocal microscope back when I was working in France. Especially the multiple one look strickingly like those pillars.

[Dan Sonye]

Sorry if I'm stating something that's already been discussed, due to it's simplicity...

But...

Could the columns and the diffracted tops, exist in two different layers of air, with small transitions between the two, where one layer allows the formation of ice crystals that produce the laser like light columns, and the layer above containing conditions more prone to produce ice crystals that produce a more diffracted cone of light?

Does the coning of the light, where there are multiple columns, occur at the same heights?

Cheers,
Dan

[lilywhite]

THe lights flare out at the top because the photo was taken inside looking out through a window that was slightly curved at the top.

[rustylypps]

I believe that the fan effect is a lens effect. the culmination point is the most concentrated light at the top of the pillar and after culmination the light fans out!

[Rob Instigator]

I love pillars of any type. This is a beautiful picture. It is an amazing thing what ice crystals can do to light in our atmosphere

[johnhe]

The light source may not be a point source but a wide arc source and may be focused by a concave reflecting mirror to a soft focus mid-pillar, which results in a cone beyond the focal point and the central light pillar is more intense as the center of the source is reflected back on itself by the mirror. Sounds like grade eight science to me.

[salmo]

The one thing I noticed was all the light pillars fanned out at the same height so maybe at that height the density of ice crystals change

[pauln]

The light is being reflected from the underside of a horizontally aligned flat ice crystal so I think we can exclude any kind of lensing, diffraction or interference effects.

We have to remember that the lights are not directional so light is spreading from the source in all directions equally. Because the ice crystals are nearly horizontal with small random variations in angle, only crystals that are close to the line between the camera and the light source will reflect light to the camera. This will cause the pillar effect. Remember that the pillar only appears to be above the light source. In fact it will be centered over a point halfway between the observer and the light source. The tapering will be caused by the parallax effect of the lower end of the "pillar" being so much closer to the observer than the higher parts.

The fan at the top is almost certainly caused by greater variation in the orientation of the ice crystals. Again, remember that the light source is projecting in all directions equally. With greater variation in orientation, ice crystals further from the line between the camera and the light source will be able to reflect light to the camera. This will cause the pillar to broaden but lose intensity as fewer crystals near the direct line will have the correct orientation.

The stability of the crystals near the ground will be due to drag creating a layer of still air effectively trapped by the buildings and trees. The fans indicate a boundary between the more freely moving air above the trapped layer. This effect is well known to hot air balloonists and pilots of small air craft, who are able to take off in dead still conditions on the ground only to experience a shear zone and steady breeze a few hundred feet up.

[apodman]

How about a thin vertical radial section of an Airy Disk?



This idea would rely on two phenomena based on the geometry/orientation of the ice crystals. The first would create the Airy disk diffraction rings. The second would limit the observer's view of the rings to a tall narrow window. The light would be in the center of the Airy disk. The first bulge above the light would be the first diffraction ring. The trumpet would be the beginning of the second diffraction ring before it fades beyond recognition. If all this were to be true, a light positioned higher in the air should produce a bulge and trumpet both above and below.

I liked the idea that one geometrical principle and one statistical principle produce the observed phenomenon. This contrasts with the suggestion above that two geometrical principles might be responsible. The thing I don't like about the statistical part is that it relies on a distributed atmospheric phenomenon as part of the explanation. I'm happier looking for an answer in a static uniform diffuse fog of crystals. I would expect the crystals to be aligned nearly parallel in one plane but at random angles in the other direction.

[neufer]

<<Sigulda, Latvia, has been called the "Switzerland of Vidzeme".

After the restoration of Latvian independence in 1991,
an emphasis was placed on...improving the town's TOURIST sector.

Points of interest: Vertical wind tunnel, owned by Aerodium Latvia.

Sigulda Publicity Stunt= Bright searchlight + Aerodium Vertical wind tunnel + snow crystal input (from bottom)


http://spaceweather.com/submissions/pic ... 501854.jpg

[apodman]

If you don't like the Electric Universe theory - you're not gonna like this explanation ...

Thanks for the warning. I didn't read a word of it. This is a scientific forum. EU is not science and does not belong here.

[apodman]

Sigulda Publicity Stunt= Bright searchlight + Aerodium Vertical wind tunnel + snow crystal input (from bottom)

So are you telling us that the publicity stunt you describe is actually responsible for the appearance of the 090112 APOD? If so, what is RJN's role in asking for explanations?