Hi Jackie,
I think that what you have there is a circumzenithal arc (CZA), possibly with a
matching circumhorizontal arc (CHA). They are caused by the sun's rays
refracting through ice platelets high in the atmosphere. You need the sun low
in the sky for them to be seen. There are other ice haloes around the sun,
particularly with 22 degree and 46 degree arcs, but the CZA and CHA are
generally reckoned to be the most impressive and colourful, second only to the
normal rainbow. You are very lucky to have seen it (I'm jealous) and
congratulations for getting a photo.
Regards,
John-------------------------- Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
From: Jackie Jones <jac...@waitrose.com>
To: sundial@uni-koeln.de
Sent: Wednesday, 17 August 2016, 15:24
Subject: A Strange Rainbow
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Sundial folk, I know this is not really sundial related, but I am sure
someone will be able to explain this odd rainbow. The picture was taken
yesterday just before 6pm British Summer Time on a hot sunny day. Looking west
to the low sun, there was a rainbow above it with the ends of it curving
upwards. Below it there was a very faint second one in the same curve. How
does this happen on a dry day; normally the sun is in the opposite direction to
the rainbow? With best wishes in anticipation of an explanation,Jackie Jackie
Jones50° 50’ 09” N 0° 07’ 40” W
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