Elliptische Halos (Diskussion)

[Bertram Radelow]

hi Claudia,

ich möchte das Interesse darauf lenken, dass auch Untersonnen elliptisch sind. Eine mit rotem Rand habe ich ja schon publiziert, jetzt habe ich mal eine unauffällige US 200% kontrastverstärkt, und auch da sehe ich zwei (elliptische) Farbfolgen - von innen grün-rot-grün-rot:



Erklären kann ich natürlich nichts. Ich nehme aber an, dass es für Dein elliptisches Doppel fast die gleiche Erklärung gibt (zwei Lichtwege?) wie für meines. Bei meinem ist nur eine zusätzliche Spiegelung dabei und mehr Streuung, sodass alles verwischt.

Und wie Du Dich ärgerst nicht auf Hohlräume geachtet zu haben, ärgere ich mich, nicht auf die unmittelbare Sonnenumgebung geachtet zu haben. Aber es ist mir einfach zu gefährlich... die "Unterländer" haben keine Ahnung WIE hell die Sonne ohne störende "Luftfeuchtigkeit" ist. Ich werde mir ein -12er Graufilter besorgen und nächstes Jahr auf die Sonnenumgebung achten. US sind an der Parsenn relativ produzierbar oder wenigstens berechenbar zu beobachten.

Bertram

[Claudia Hinz]

Hallo Bertram,

vielen Dank für Deine Studie. Hab jetzt mal an meinen Untersonnen herumprobiert, sie geben ein ähnliches Bild ab. Aber ich kann so unscharf maskieren wie ich will ... und auch mit stacken hab ich's versucht, es ist und bleibt eine elliptische Fläche, Ringe bekomme ich keine herausgekitzelt. Aber die hatte ich ja damals, als ich die elliptischen Ringe um die Sonne hatte, um die Untersonne auch nicht.

Wir Zeit, daß es wieder kälter wird und wir auf die Ellipsenjagd gehen können ... das nächste Fall werde ich auf jeden Fall versuchen, die Kristalle abzulichten.

LG Claudia

[Michael Ellestad]

Folks,

Since we are doing elliptical halo discussion I want to let you guys know I got one this past weekend on Saturday and since the sun was low the ellipse was very enlongated and I got pics of it. In addition to getting the halo I go tnice corona and iridescence. You can see the pics on my facebook page. I hope they will be up on the blog soon.

Regards,

Michael

[Alexander Haußmann]

Dear all,

yesterday I got a message from Nicolas Lefaudeux who made a zoomed view of the hollow column simulation:



He commented on this simulation "there is definitely nothing elliptical on the zoomed view...". So it seems that hollow cloumns won't be the key to elliptic halos.

@Michael: I'm looking forward to see the pictures. I'm not used to Facebook, so I have to wait until they are shown in the blog. Did you make your observation at some special place, e.g. near snow guns?

The last halos I've seen were also elliptic, but in a different meaning. Last saturday I observed 22° and 46° rings on the ground in divergent light within frosted snow grains. Reminded me a lot of the "old times" when Richard Löwenherz and I wrote about them (http://www.meteoros.de/halschn/schnee1.htm).

Regards,
Alex

[Michael Ellestad]

Alexander,

I got mine in AC clouds that had precipetated into a layer of ice crystals. I was not near any snow cannons and the farthest ski resort which is called Perfect North is over a hour and half drive and is near western Ohio USA. would of love to have been at perfect north would of gotten some awesome diamond dust halos.

Regards,

Michael

[Alexander Haußmann]

Hello Michael,

I presume there were no "common" halos accompanying the elliptic rings?

It seems that you are either very lucky or well experienced in observing elliptic rings. Maybe I'm not very attentive to phenomena near the sun, but I regularly see coronas and iridescence. Maybe I only realize things I already know, or it is due to the poor weather conditions in lower Germany.

What do you think about multiple scattering by swinging plates or obtuse pyramids?

Regards,
Alex

[Michael Ellestad]

Hey Alexander,

Yes there was other halos and they were upper and lower pillars inside the ellipse. As far as crystals go I think like you say obtuse pyramidal crystals with a plate like habit and plate orientation form the elliptic halos. I've ran simulations with good results. In Finland back in the 90's and observor got a sample during a diamond dust elliptical halos and sure enough the sample contained a bunch of obtuse pyramidal crystals. I don't think multi-scattering would do.

Yeah I am very experienced in getting ellipses and thats because elliptical halos always form in Altocumulus (AC) clouds when they precipitate into ice crystals.

[Alexander Haußmann]

Hello Michael,

I got a message from Richard Löwenherz who observed elliptic rings during a bicycle trip to Northern Russia in February 2010 (river Izhma, republic Komi). They were visible during three consecutive nights around the moon in thin, vanishing Altocumulus clouds. 10-20 minutes after the rings became visible, a light precipitation of plate crystals was recorded at the ground (looking like "sectored plates"). When the clouds moved on, the snowfall stopped and the elliptic rings faded away shortly after that. This sequence of events repeated itself several times.

Radius and shape of the halos varied continuously, even within one visibility cycle. Most of the time two rings were visible, sometimes only one. The maximum radius of the second ring in vertical direction was about 6°. During the second night, only the upper parts of both rings were visible. The temperature was about -20°C, no accompanying halos were observed.

So we have precipitating Ac clouds once again, and strange plates. It seems that obtuse pyramids will win the race.

Concerning the collected crystals from the 90s I suppose you mean Sillanpää et al., Applied Optics 38, 5089 (1999).

Kind regards,
Alex

[Michael Ellestad]

Alexander,

Never thought sectored plates would make ellipses I figure it would be obtuse pyramids. Did Richard get any pics at all? If so I would like to see them. Just like Richards display the AC clouds were precipetating into crystals forming the halos. In the big display I got in 2003 I at one time could see up to three ellipses other times there was one of two. I also timelapsed it as well.

Regards,

Michael

[Alexander Haußmann]

Hello Michael,

maybe my interpretation of Richard's record was a little too straight - the original statement was "plate-like crystals with shapes that could be described best as sectored plates". I sent him a copy of the obtuse pyramid paper, and he found some similarities in the crystal shape. I would post the images here, but I'm afraid of copyright infringement.

Unfortunately, there are no good photos from the halos available due to technical reasons. The story of a bicycle tour through Northern Russia in winter may sound strange, but it really happened (http://www.lonelytraveller.de).
Some additions/corrections to the last posting: In the first 2 nights, the moon was quite high (40°), in the third night lower (20°). The clouds looked more like Sc in the the last night and light pillars were visible at car lights (long) and the moon (short).

So all in all I'm convinced that Richard and you saw the same kind of phenomenon. I'm not sure if there are other elliptic rings with a different origin possible. For your case, the crystal samples and simulations give strong evidence, but the existience of such obtuse pyramids still remains a crystallographic mystery.

Regards,
Alex

[Michael Ellestad]

Yeh Alexander,

Until we get more decent crystal sample during elliptical halos we may never know what type of crystal forms them. obtuse pyramids form elliptical halos extremely well in halosim program. I hope to get some more of these. My record number of elliptical halo observation was 2009 and got 4.

Regards,

Michael

[Alexander Haußmann]

Hey Michael,

I just saw your pictures in the ursa.fi blog. Great work! Does the colored cloud fragment at the right side of the ring in the first picture belong to the halo or do we see some iridescene/corona effect there? Do you have any idea why the axis of the ring is tilted from the vertical direction?

Alex

[Michael Ellestad]

Hey Alexander.

The colored cloud fragments are not the AC that vanished into the halo making crystals its a regular cumulus. I have a photo in a elliptical halo I got in december 2005 where near the halo you can see iridescent AC cloud associated with the halo. The reason why the axis of the ellipse is tilted to the right is because I was trying to get as much halo into the pic without getting the sun inmy eyes and also just from sheer excitement too!!:) I was packing my car up in preperation to leave for the weekend to visit my brother and I looked up and was like HOLY FRITZ!! gotta get this elliptical halo! I seen elliptical halo earlier that day but was too faint or to short-lived.

I hope for more of these Alexander along with rarities like odd radius halos, wegener and other arcs from column crystals.

PS: Glad you enjoyed my pics. Need to submit one for the pic of the month on the AKM site.

Regards,

Michael

[Claudia Hinz]

Les hat heute eine dritte Beobachtung von elliptischen Halos in Eisnebel auf OPOD:
http://www.atoptics.co.uk/fz582.htm

Im Gegensatz zu den Virga-Ellipsen sehen die Eisnebelhalos alle gleich aus, was meine Vermutung, daß es sich um Erscheinungen mit unterschiedlicher Ursache handelt, nur noch unterstreicht.

Die Ellipsen von Michael schauen völlig anders aus...

LG Claudia

[Claudia Hinz]

Habe heute einen interessanten Artikel von K. Lenggenhager bekommen, wo Ellipsen mit Hilfe eines Hohlspiegels simuliert wurden. Interessant ist, daß damals schon die Kristallform eines an den Rändern dünner werdenden Eisplättchens vermutet wurde.

http://dl.dropbox.com/u/3038661/Bottlinger.pdf

LG Claudia

[Alexander Haußmann]

Hallo Claudia,

leider komme ich in der letzten Zeit nicht sehr regelmäßig zum Lesen des Forums, daher erst jetzt eine Reaktion von mir.

Ist das erste Bild in dem Artikel möglicherweise das früheste Foto der Bottlinger-Ringe überhaupt? Ich nehme mal an, der Artikel stammt so aus der Mitte der 70er Jahre.

Die Idee mit den spiegelnden eingedellten Kristallen ist ja gar nicht so weit weg von den brechenden mittig verdickten Kristallen für die elliptischen Ringe um die Sonne. Zumal auch die verdickten Kristalle einen ähnlichen Spiegeleffekt verursachen könnten. Dann würden die Bottlinger-Ringe zusammen mit elliptischen Halos auftreten, was allerdings nicht unbedingt zwangsläufig der Fall sein muss, siehe die bisherige Diskussion zum Thema.

Gruß, Alex

[Claudia Hinz]

Könnte sein, denn Bottlinger selbst hat ja keine Fotos machen können (siehe Beobachtungsbericht: http://submoon.files.wordpress.com/2011/01/bottlinger-2 und http://submoon.files.wordpress.com/2011 ... nger-3.jpg

Habe auch in den vorhandenen alten Büchern keine weiteren Fotos finden können.

Ansonsten hoffe ich, das Ding nochmals irgendwann zu sehen, dann werde ich auf jeden Fall auch die Kristalle ablichten, koste es, was es wolle ;O)))

LG Claudia

[Claudia Hinz]

Korrektur:
Lynch, Gedzelmann und Fraser haben ein Bild von 1922 drin:
http://www.thulescientific.com/SubsunsB ... O_1994.pdf

Allerdings kann ich das Bild in meinem Perntner-Exner nicht finden, obwohl ich die beschriebene Ausgabe von 1922 habe, weder auf Seite 397 (da tummeln sich die Parrybögen) noch irgend wo anders...

LG Claudia