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.

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