Pyramidal halos 7-10-19

Before leaving for work yesterday, I saw some cirrus clouds moving in and in a short time later 18 and 23d halos along 18d plate arcs, and bright upper 23d arc appeared. The display went on for a while and when the sun was high enough, a bright and well-defined lower 23d plate arc formed. The lower 23d plate arc in this display is my best to date.

Odd radii halos outbreak in the Czech Republic

There was an odd radii halos outbreak in the Czech Republic and Hungary in the past few days.
Multiple rare halo forms were captured.
Let me show you some of the photos:

These were taken by Jiří Kaňovský from Černotín, Czech Republic:

He managed to capture 9° contact arcs, 9° parhelion and 24° parhelion among others. Uppercave Parry was captured, too.

These were taken by me:

I am very confused about the halo forms captured here. First I thought I captured 18° parhelions, but now it turns out those are probabaly 20° and also 35° column arcs. There is also a faint lower 23° parhelion. 9° contact arcs are possibly captured, too.

The sun was 62° high at the point of the photoshoot.

I managed to stack multiple photos and edit those in Photoshop to bring out the halo forms.

Can anyone confirm that those are indeed column arcs?

Here are some .NEFs (Nikon's RAWs) if you're interested:

https://1drv.ms/u/s!ArJV0E31n7WMg0jl3Lh02eZjZy0p

Lower 23 degree plate arc observed in Ohio USA 5-9-06

While on break time at work I decided to check the sky and saw a 22d halo with a rather suspicious brightening that encircled the lower half of the halo. As the cloud moved on a rather bright arc appeared and I thought circumscribed halo no it was a lower 23 degree plate arc!! I could tell because there was no circumscribed halo which goes all the way around while lower 23 degree plate arc tails off away from the circular halo. Weak 18 degree halo was also observed. The photo has been given an unsharp mask to show the halo better. You can clearly see the arc tailing away from the halo while diminishing in intensity

Lower 23 plate arc observed in Chile

Lower 23 plate arc is a rare halo, that, as far as I am aware, has been observed and photographed only once. This was in Chile on 28. November 1997. Now the lower 23 plate arc seem to have made another appearance - and again in Chile.

The accompanying picture is from halo display seen at Aucanquilcha volcano on 3. Debember 2005 by J. Ruoskanen and I. The image is stacked from 63 individual photos taken during 20 minutes. Unsharp masking has also been used. The simulation is made of populations of random and plate oriented pyramid crystals. Halos are 9°, 18°, 20° and 23° circular halos and lower 23 plate arc (23 lpa). Sun elevation change in the photos was from 71° to 75°, the simulation is for 73°.

Lower 23 plate arc is probably not that rare halo in itself. It's just that resident observers are lacking from the locations where sun regularly rises high enough for it to be seen.

Simulations are made with HaloSim and stacking with Registax.

More stacking technique halo images can be seen here.