Column display with a magnificent Wegener arc from southern Alaska, July 9th, 2023

Dear halo enthusiasts,

it certainly has been a long while since the last entry here, but just recently we received an extraordinary halo report which is definetly worth posting. This may be a great way to revive this blog!

Dr John French sent us photos and additional data from an observation made by Jill Quaintance and Don Kluting from Petersburg, Alaska, on July 9th, 2023. All image credits go to them. John has recently been travelling with Jill in the Antarctic peninsula and the Falklands and they discussed the subject of halos. This is how the halo display of last summer resurfaced.

Here you can see the time and place of the observation in Alaska:

The halo display, recorded around 12:21 pm at a solar elevation of about 55° includes a complete circumscribed halo and parhelic circle, as well as a faint 22° halo and right 120° parhelion (“paranthelion”). However, the most striking piece is the well-developed loop of Wegener’s anthelic arc around the zenith. At the intersection with the parhelic circle, we can see a distinct bright spot, either due to the confluence of three white arcs or the somewhat elusive “anthelion” halo species itself. John also prepared some labels for the prominent halo species.

Note: In the classification used in the “Arbeitskreis Meteore” (and maybe elsewhere), the upper and lower tangent arcs would not be recorded as individual species at such a high solar elevation, as they have already merged into the circumscribed halo. But in the end, this is just a matter of nomenclature. Here is another nice picture, taken with a lower camera tilt:

John also used  HaloSIM  in order to reproduce the display in a simulation. Strictly oriented columnar prisms and an admixture of some random oriented prisms gave a satisfactory result.

We also wanted to cross-check if there might also be a Hastings anthelic arc involved. John made a simulation with some additional Parry oriented crystals:

(The feature labeled as “Sunvex Parry” is in fact the heliac arc).

As expected, the simulation also shows other species from the Parry family rather prominently. These are not present in the photographs – there is only a very slight hint of a suncave Parry in the second picture. So we can be quite sure that we have here a textbook example of a halo display dominated by singly-oriented columns and including a magnificent Wegener arc.

Let’s hope for many more nice observations in 2024! Greetings from Germany.
Alex

Reflection subsun in California

On January 25, 2017 I observed a reflection subsun in Auburn, California. This was my second observation of this phenomenon, the first of which was on February 1, 2008 and is already documented here.

The conditions between the two observations are nearly identical: The observing location, time of day, and time of year. Also of note is that both were seen following a multi-day period of heavy rains, which supplied the water that reflected the sun upward toward the Altocumulus cloud. The water had filled the Yolo Bypass, which is an area that is designed to flood during periods of heavy precipitation and lies along the line of sight between Auburn and the setting sun.

Author: Steve Sumner

On some more aspects of a display observed in Rovaniemi on the night of 9/10 November, 2016

In the previous post of this display I discussed two photos taken towards the end of the hunt, just before twilight. Now it is time to look at the photos taken earlier, from midnight onwards at another location. Please mouse over or click the photos to remove the milky veil that the systems adds as default to them.

Of the several stacks that were photographed, I made simulations of two that are shown below. Unlike the morning photos, now only one stricly oriented Parry population was needed to the explain the display’s halos from c-axis horizontally oriented crystals. So here we have a pure case of uppervex Hastings and nothing reminescent of Wegener.

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All rare halos are missing in this spotlight display, but why?

The mystery deepens. In two previous posts we wondered why some displays are great in their column orientation halos even though the crystals have well caved ends. Here we show a case that appeared on November 22, 2015 in Rovaniemi, where crystals seem not much different, yet rare halos requiring basal faces are completely absent. Even the 46° supralateral arc gives just a whiff. Poor crystal orientations can’t explain the absence of rare halos as the tanget arc is quite sharp. Had we known only about this display, we would be quite happy to explain with cavities, but knowing about the other displays, it is quite puzzling.

Marko Mikkilä, Jarmo Moilanen, Marko Riikonen

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Solar diamond dust display with 87° arc

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A stack of 40 photos. An average stack has been combined with maximum stack to show the crystal glitter of the 87° arc. The photos were taken during ~2 minutes. Sun movement has not been accounted for.

The diamond dust season is soon to arrive in Finland and it is time to wipe the dust off the equipment. In a meanwhile, here is the last winter’s starter for Rovaniemi, on October 30. The temperature during the display was -5° C, a quaranteed number for great stuff.

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