Halos on the night of 14/15 December 2016 in Rovaniemi, part II

Here is a collection of images showing an arc that looks like a downwards curving Hastings or Wegener. It's nothing new: the arc was first observed in Rovaniemi on 23 November 2015 and again nine days later in the evening of 2 December. I don't know how it is made, but it seems to occur when the display is suboptimal as compared to its best development. A halo that thrives on (relatively) crappy crystals?

In the display on the evening of 14 December 2016 this anomalous Hastgener was captured on several stacks, one of which is shown above and which also has normal Hastgener. Below are two more photos of which at least the left side one shows the effect. It was true to form, as these stages did not represent the peak of the display.

There was an additional oddity: the Hastgener / anomalous Hastgener has a kind of parhelia near the tangent arc. The feature occurred intermittently and was well visible to the eye. Below are two images showing this "parhelia", the one on the left is a single frame. The brightening seems to be also present in the main image above.

Another appearance of the mysterious Sub-Kern companion

The image above shows an arc that points towards the bulge in sub-Kern. Its formation is unknown. We captured the arc first time on two occasions on the night of 6/7 January 2016 in Rovaniemi. The current case was photographed in Rovaniemi too, on the night of 28/29 November 2016.

Judging from the crossing of helic arc and (what appears to be) Hastings over the 46° halo, the lamp must be around 3.5 degrees below horizon. I made some quick simulations. The upper one has plates, randoms, and Parry. Plate shaped Parry crystals were used to get the relative intensity of the helic arc and Hastings somewhat comparable to the actual arcs. Simulation has also subanthelic arc, and it seems to be present in the photo, although it is quite broad and diffuse. The lack of Parry arc in the actual display is rather curious.

To make sure that the mystery arc is not some kind of anomalous singularly occurring Tricker, the lower simulation was made with added column oriented crystals. Sure enough, location of the Tricker does not match.

The bulge in sub-Kern seems itself also anomalous and appears to be associated with the mystery arc. The bulge has not been photographed in the numerous displays without this arc.

Another occurrence of an anomalous Hastings/Wegener

By Aleksi Velhola and Marko Riikonen

In an earlier post we showed a photo of a weird downward curving patch of Wegener/Hastings. Here is another case that occurred 9 days later on December 2, 2015. This time we also got a nice comparison to normal “Wegstings” by superposing photos taken from the same camera position.

The anomalous Wegstings appeared on two occasions and was well visible to the eye. At both times the display was less brilliant than at peak stages, during which normal Wegstings was seen. Same was true of the earlier display on 23 November.

A closeup of normal and anomalous Wegstings appearances superposed to one image.

The crystal sample is interesting. Crystals range between plates and equidimensionals, which one would not expect from the strong column orientation halos in the display. It just adds to the ever increasing file of cases where the samples are not what would be expected. The dish was out long time, something like half an hour, so it represents all different stages of the display put together. However, column orientation halos were all the time present.