The morning was cloudy. Around 11-30 sky started to clear. After half an hour the whole sky was covered high clouds. But I did not see any halos. It seemed it was usual bad clouds, which not produce halos. Nevertheless, in some moments I saw very weak and wide 22° halo with something resembles upper 23° plate arc. Also was an episode when I saw compact CZA, which apeared without parhelia. My suspicions have only become stronger, about that I faced with subvisual odd radius display.
It was brilliantly confirmed when I returned to home and processed stacks. I was able to identify such pyramidal forms as upper 9° plate arc (possible), upper 23° plate arc, lower 24° plate arc. Also were captured 9, 18, 20, 22, 24, 35 (very diffuse, link) and 46 halos. Odd radius halos lasted 50 minutes, until 13-30. Then until the end of display (until 15-30) were captured only weak common halos, such as upper tangent arc, parhelia and 22° halo.
It was fourth display since 15 February, which includes pyramidal halos.
Not bad. How long time interval is that stack and how many frames?
ReplyDeleteMarko, this stack includes 330 frames and covers 22 minutes
Deletenice catch! i like the term "subvisual odd radius display", it is perfectly adapted to those OR displays.
ReplyDeletethis is what most of the OR i got with the halocamera are: revealed by stack and/or B-R, but not visually observed as odd radius, thought with the experience i recognize this type of displays visually with broad, undefined halo in 22° area.
i got on average 50 OR displays per year with halocam in Paris, so you are totally in line with your 4 cases since middle of February.
the sat images https://www.youtube.com/watch?v=dDnUDTSJ_yY also show that it is a nice case of cirrus in full sublimation at that time over St Petersburg
I also like the term "subvisual"; I remarked only yesterday in a private e-mail discussion that this term perfectly captures the conditions described above. I for one would be very happy if its usage was adopted widely by the halo community.
DeleteWow, it is a really clear example of the sublimation of cirrus clouds. I see these satelite images only just now. By the way, do you plan on writting new posts on opticsaround or on the halo vault, with new or unpublish results of halocamera's work? It would be great to see it.
DeleteI am glad you like this term. I used it by anology with the term "SAR arc" (subvisual/stable auroral red arc).