It was a weak odd-radius display which contained not only familiar pyramidal halos with radii of 9, 20, 24 and 35 degrees, but also a mysterious 13° halo! You can notice this diffuse 13° ring between 9° and 20° halos on the image above. You can also notice that the 20° halo is brighter than the 22°. The 35° halo is clearly visible on the image below.
With the naked eye only parhelia were visible during the display. The display was short and lasted about an hour and a half.
Did you have a hunch that there would be more than parhelia?
ReplyDeleteNo, usually, it is always a surprise. It is impossible to know what one can find on stacks, especially when they was taken during a display which was weak and wearisome with the naked eye.
ReplyDeletehas that 13d ring ever been seen with naked eye?
ReplyDeleteAs far as I know, this halo has been found only in processed images less than 10 times for all time
ReplyDeleteI think in the very first 13° halo display at South Pole in December 1998 it would have been visible to the eye. That's because I recall the halo being well visible in a projected slide (that I think Jarmo showed) in the Bad Honnef Light and Color conference. Such a halo should have been discernible through convex mirror. But it is of course easy to miss something of which exitence you don't know.
ReplyDeleteThe South Pole display had also 5-6° degree halo. That one has not been photographed since then.
Has any work been done on the relative brightness of odd radius halos? Is it just the quality and distribution of the crystals in any given display as to why one odd radius halo should be brighter than another?
ReplyDeleteEvery simulation is a work on relative intensities of halos. If it is a real display you are simulating, you adjust the crystal shape until there is a match.
ReplyDelete