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This morning I was pleasantly surprised while photographing lenticular
clouds over Socorro, New Mexico. I was not paying much attention to the
sun at first, since it was behind altocumulus clouds, but when it rose to
an altitude of 20 degrees, I noticed an extended but very diffuse light
pillar up to 10 degrees below and 15 degrees above the sun. There was a
curious silvery white glow in the cirrostratus clouds around the sun.
I found this a bit unusual for such high solar elevation and started
photographing the area. A few minutes after this an elliptical halo
formed
in the glow, practically only visible above the sun, and extended about 8
degrees away from the sun in its vertical major axis. I estimated the
width (radius) to be around 5 degrees.
The halo was silvery white and formed in jetstream cirrostratus (i.e. not
directly related to the altocumulus and lenticularis).
I made between 40 and 50 photographs using a Nikon D100 and Nikon FE. The
accompanying photos were taken using the D100 with 35mm Nikkor lens (the
D100 has a 1.5x field crop compared to 35mm film). I crossed two
polarizers and held these in hand so the sun's disk remained visible, thus
the shape and extend of the elliptical halo can be
estimated. Unfortunately the halo was already gone by the time I could
start photographing using these polarizers and I fear those photos are
little useful.
Time of start of my observation was 7:30 MST and the halo lasted about 5
to
10 minutes. The glow/light pillar remained however, and is still visible
as of the time of this writing (9:30 MST). There has been a stationary
lenticular cloud obscuring the region above the sun for the past hour, so
I
don't know if the elliptical halo is still there.
I was lucky that I had all my camera equipment with me at the time. This
is the first time I get to see this type of halo - I have been looking for
it for years. The fact that I see this one just after Michael Ellestad
saw
and photographed one a few weeks ago seems to be utter coincidence, since
I
haven't been paying more attention to the sky than usual to search for
this
halo.
If anybody is interested for research purposes I can send you more images
and give you the exact time and location of each photograph. The
accompanying two photos were taken at 62mm (image 052, 7:30) and 40mm
(image 061, 7:35) with a 1.5x field crop from the D100.
Harald Edens
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