Tuesday, 28 December 2010
"Upper parhelia" over the Alps
On 13 December it was cold and windy on Mt. Wendelstein (1838m) in the German Alps with temperature of -17°C and huminity over 90%. The whole day ice dentrids glittered in the air ( 1 ). For 6 hours I could observe a partly bright subsun ( 2 ). Actually I've seen 2 subsuns in time, the "main subsun" at a lower blanket of clouds and a second displaces a bit to the right in near crystals, based on tilted ice plates (caused by the wind). It was very difficult to photograph it because of the radiant brightness of "main subsun", but you can see the second, as the "main subsun" disappeared a short time. ( 3 - 4 - 5 )
Partly shaped imaginary arcs on this: ( 6 )
A short time before sunset in a single cirrus cloud was formed a colourful parhelia. ( 7 - 8 - 9 )
It faded a short time before sunset at 16.17 CET. ( 10 )
From 16.25 to 16.35 CET the parhelia clearly appeared again in the same Cirrus stripes. ( 11 - 12 - 13 - 14 - 15 )
I've not a explanation for this. I've observed a little displaced parhelia in far-off Cirrus (1-2deg) a couple of times, but never before such a clear sundog to this negative altitude.