High cloud 44° parhelion is still waiting for its capturer. A chance to try for one came on September 28 this year in Kontiolahti, Finland, when a cirrus floe containing a short-lived blinding parhelion moved out towards the appropriate position.
I had already camera snapping photos at 10s interval, but changed it to 4 seconds when I estimated the leading edge of the floe had reached about 44 degree distance from the sun. The b-r image above is 84 frame stack from the time it took for the floe to pass the 44-46 degree azimuth and shows indeed a dark spot indicative of red color. But it looks to be too far out for 44° parhelion when compared to the 46° halo in the image. Probably we are looking here just at a segment of 46° halo or 46° lateral arcs crossing, or both, but proper measurements using starfield may still be worth doing.
Even if the result seems negative, it thought to share this to pay attention to situations where high cloud 44° parhelion might be a prospect. Below are other relevant images and some more info.
Bgr and usm versions.
At 13 degree sun elevation 44° parhelion is inside 46° halo, which is not the case with the spot in the observed display. The other half of the simulation has column and Parry population as the display had halos also from these crystals. Made with HaloPoint.
The short stage during which bright parhelion appeared in a cirrus floe. Photo interval is 10s.
Here is shown the first (top) and last (bottom) photo of the 84 frame stack (middle) from the period that it took for the floe (delineated) to pass 44-46 degree mark.
Uncropped versions of the 84 frame stack, br and usm. Notice the lacking of uppervex Parry. With regular hexagons at 13 degree sun it should be of equal brightness with the uppercave. In stacking, when sun is tracked at this solar elevation range, uppervex gets unfocused and uppercave focused relative to each other due to their sun elevation dependent movement which are in the opposite directions. But as the stack has only 0.5 degree sun elevation change (from 13.3 to 12.8 degrees) the effect should be negligible. Thus the absence of uppervex (or almost absence, there seems to be a ghostly suggestion of it in the image) tells of tabular crystals. A simulation with 0.7 1 1 0.7 1 1 shape modified crystal in HaloPoint reproduces the situation and this is what has been used in the simulation above (0.2 uniform deviation for the two faces). If somebody knows other similar Parry displays showing evidence of tabulars, I am happy to hear. I think I knew one, but have forgotten about it.
In Germany they had this display much better:
Marko Riikonen
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