Elliptical lunar halo

April 25, 2013. Elliptical lunar halo: Full Moon is approaching and that means that you will see ice halo around the moon. April 22 Darrel Laskombl Soynchula of settlement, British Columbia (Canada) saw an unusual halo. It was not round, as usual, and elliptical:

"It seems that I had not seen an elliptical halo around the moon — said Laskombl. — I looked up and just stared for a minute. Then he ran home behind the camera. I managed to photograph it before it's gone. "

Les Cowley, an expert on otpike the atmosphere, a phenomenon commented: "A few elliptical halo seen over the past few weeks in Europe and the U.S.. Something strange is going on in our skies! "

"These unusual ice halos is much smaller than standard 22 ° halo, surrounding the Sun or the Moon — continues to Cowley. — In the small circle of the halo formed by refraction of light in shestidesyatigradusnyh ice prisms. For education small elliptical halo Need more narrow prism, we think fit hexagonal plate crystals with a small tip of the pyramid. The problem is that these crystals are not physically, and computer simulations, where this type are not very good predictors of the halo. Alternatively, the effect of wedge portions can give small crystals like snowflakes. Whatever the cause [elliptical halo], they are rare and mysterious! "

Translation: Anastasia Antoshkina
Source: SpaceWeather.com

 

FAQ:

A small halo — this rainbow circle around the sun, the corner radius — about 22 degrees. The ring is closed (ideally, but often observed only fragments). The inner edge of quite sharply limited, painted in red color. This is followed by yellow, not bright, rolling in white. The sky inside a small halo often appears darker than the outside.

Types of halo:

  • 9 ° halo (van Buijsen's halo)
  • 18 ° halo (Rankin's halo)
  • 20 ° halo (Burney's halo)
  • 23 ° halo (Barkow's halo)
  • 24 ° halo (Dutheil's halo)
  • 35 ° halo (Feuillee's halo)

 

Elliptical lunar halo

Clickable image.

 

Guillaume Poulin made this perhaps the most successful shot [photo left] elliptical halo in the national park of Mont-Megantic, Quebec, Canada. He took pictures of stars at a temperature ≥ 15 ° C.

"On the way home we noticed that the mist in the air began to turn into tiny crystals that fell like snowflakes, and at the same time the Moon was formed halo. After a few minutes there was more halo twice first. "

The moon, which rose to 38 °, only the first quarter was over. To catch a halo had to overexpose, but the shape of circles is quite discernible.

Elliptical halos are rare, fleeting and mysterious. Perhaps they are related to an even rarer rings Bottlingera [Bottlinger's rings, ellipse around subsolntsa, comes in two sizes: 1x Bottlinger's ring, 2x Bottlinger's rings]

Elliptic halo — small, they may be two or three oval ring. In most cases, they are seen in Altocumulus clouds, but also can be a source of crystals of ice fog. The rings may be of different angular size and seems to depend on solar or lunar height. The lack of reliable observations and crystal samples makes it difficult to analyze.

Guillaume made some great shots. They detail see three rings. The inner ring may have a bluish and inside the second ring definitely has a reddish hue — they show that the refraction of light played a role in the formation of this phenomenon. Another tip — different brightness for the rings and the way they are shifted with respect to the Moon.

We are fortunate that some images show faint, but quite identifiable stars, which allow fairly accurately determine the size of the rings. The angular size of the second ring of 5,6 °.

Do we understand how to form elliptical halo? Their small size may be an indication of refraction in crystals only slightly inclined relative to each other. This is in stark contrast to 60 °, which are the cause of common 22 ° halo.

Perhaps because of the rings appear flat pyramidal crystals. Presumably crystals float substantially horizontally, as well as conventional hexagonal plate. The same crystals were used in the simulation rings Bottlingera, although the formation of the latter could occur in other ways.

The left is a model of the beam path, created HaloSim to match the size of the rings and the change in intensity. Crystals have been used for modeling, the upper and lower bounds of which were rejected by 3,5 ° from the horizontal. This corresponds to Miller index about (1, 0,? 1.35), which is absurd terms of crystallography. Facets usually repeated plane of atoms and ions in the crystal lattice and give the Miller index expressed simple integers. One exception is for snezhinkopodobnyh crystals with a tree organization ice processes.

Simple crystals creating a halo right size. There are three different paths of rays through the crystal faces that form three rings, similar to those observed.

The similarity is encouraging and it is appropriate — but not as much as in the simulation of other halo. It is tempting to think that some re-modeling — with separate changing the angle of the upper and lower edges, placing the flat tops from above or below, and the deviation from the horizontal — will help the proof. It is a challenge. We have a theory that requires unusual crystals, and assumptions that are not quite true.

Download HaloSim and try it for yourself!

Translation: Anastasia Antoshkina
Source: Atoptics.co.uk

 

Elliptical lunar halo

March 23, 2013. Elliptical halo — an extremely rare at the famous site OPOD (which publishes the most interesting pictures of optical phenomena from around the world), only a few pictures of the halo (123456), And blog it occurred only once.

To create the model of the elliptic halo use flat pyramidal crystals (but such crystals are not by nature is physical, the water simply can not freeze in such icy snowflake), other crystals do not give a perfect match of light transmission.

Time of observation: March 17, 2013, Bryansk, 21:32 (+4:00):

Source: ice-halo.net

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