Showing posts with label pillar. Show all posts
Showing posts with label pillar. Show all posts

Tuesday, 4 July 2017

Cross and Crescent from 1664

From The Graphic Collection of the Hungarian National Museum. MTKcs.9613.T. and MTKcs.9612.T. Reproduced with permission.

On 3 August 1664, a curious phenomenon made the inhabitants of Pápa, Hungary wonder. Between 11 and 12 pm a shining white cross appeared in the sky together with the crescent Moon. They seemed to be fighting for about an hour, either the one or the other overcoming, but by midnight the Moon had deferred to the cross, which – according to the contemporary description – might be a good omen.
 
Two anonymous engravings eternalised the apparition, both from the late 17th century. They are part of The Graphic Collection of the Hungarian National Museum, a collection which also contains a few etchings depicting historical halo observations. These have earlier been dealt with in a Hungarian language article [Farkas A., Kiricsi Á., Klemm L. (2011) „(R)égi csodajelek, 17-18. századi halójelenségek a Magyar Nemzeti Múzeumból”. Fizikai Szemle 61 (12): 407-413.], and are going to serve as the basis for the next historical mini-series of The Halo Vault.

Of course, we cannot say with certainty what the 17th century inhabitants of Pápa saw exactly, but presumably it was a halo phenomenon. The description might indicate a lunar pillar with a stretch of a cloud, or even a pillar with upper tangent-arc. The time given in the contemporary accounts is rather problematic, however. The Moon was almost full and already 21° high in the sky at 11 pm, so the implied lunar pillar can certainly be ruled out. But if we continue theorizing, and suppose that the date given is still according to the Julian Calendar, the idea of a pillar is much more likely, as the Moon in the given time-slot was between -3,5° and 6° (though not in such a thin crescent shape as in the images). In Hungary the Georgian Calendar had been in use for almost 80 years in 1664; but we know that at least one of the two engravings is by a German master, and in the Protestant areas of Germany the adoption of the calendar reform was much slower. In some parts the reform was only enacted in the 18th century. But again, this is only a hypothesis, we cannot fully decipher the two images and their descriptions.

The heavenly cross appearing in the sky was considered a mysterious sign, and as usual with such unaccountable phenomena, reports tried to authenticate it in various ways. As we learn from the text below one of the engravings, the cross was not only visible in Pápa, but also some 120 kms away, near Vienna, the seat of the Habsburg monarchy. The other document mentions that even soldiers witnessed it, thus giving the account more credit.

The cross subjugating the Moon could easily be considered a good sign in 17th century Hungary. Most of the country at that time was under Ottoman Rule, and the Christian cross overcoming the traditional Muslim symbol of the crescent must have been thought by many as a symbol of divine providence against the Turks.

By Ágnes Kiricsi

Thursday, 2 February 2017

Subparhelia and sub 120° parhelion on ice surface

average stack of 15 frames
In the morning after new year's night, I noticed through a window cirrus clouds, and I went to observe. While I was waiting for the appearance of halos, I noticed weak subparhelia on the ice surface. Out of curiosity, I decided to look for a place where they could be brighter, and I found it (1, 2). It was quite a small area near a coast, almost all sides limited. There I saw not only bright subparhelia, but also clearly visible sub 120° parhelion in pillar form.

maximum stack of 3 frames
It was perfectly visible even when I did not move. The temperature was negative only at night until this morning. In the previous day it was positive (around +4 degrees of Celsius), as during of the observation (0...+1). 

At that time, while I was shooting halos on the ice surface, in the sky appeared parhelion and 22 degree halo (3). Later the upper tangent arc was spotted in cirrus clouds (on the stack also well visible supralateral arc - 4). At the end of the day, I also noticed weak and wide circumzenithal arc (5) from low sun.

Date: 2017-01-01

Thursday, 18 May 2006

A halo caused by light reflected from water surface

This subsun-like pillar on front of dark cloud was photographed by Jenni Elina Holopainen on 18. May 2006 in Pyytivaara, Finland. The position of the pillar is apparently the same as that of the Sun's behind the cloud, which is better revealed by the cloud rays in another photo.

So how this is possible? The explanation must be a reflection of sun light from still water body and further reflection of this light from ice crystals that are precipitating from the Altocumulus clouds seen in the picture. Thus we are looking here - not at the subsun - but at "supersun".

The best sun pillars are usually seen in the icy virga of the Altocumulus clouds. This is because virga can consist of very big plate crystals that have plenty of horizontal surface to reflect sun light. Thus it would be expected that if this phenomenon were to occur, it would be Ac virga if anything. In high clouds it's impossible to see this, becase there is nothing behind the crystals to block the Sun. And when diamond dust occurs, waters are usually frozen. Thus ice crystals precipitating from middle level clouds is perhaps the only possible formation for the phenomenon Holopainen photographed. In yet 
another photo taken by Holopainen, a curved Ac virga can be seen in the middle of the picture above the lake. This is the lake that most likely was responsible for the reflection.

Actually this is not the first observation we have of this kind of phenomenon. In the end of 90's in Oulu a pillar of light (with no distinct subsun like appearance) was observed in a similar manner.

Sunday, 5 March 2006

Venus Pillar and Star Pillars




















Neither sun pillar nor moon pillar is not a rare halo. But a "venus pillar" is hardly found. 

The photo was taken by Myao (his handle), who was searching for Comet Pojmanski. It was before dawn of Mar 4, 2006, in Tsukuba, Japan. 

He also observed short "star pillars"! A close-up image can be seen in his site (in Japanese).

by Yuji Ayatsuka