Typically, this would indicate ice crystals in the upper atmosphere. A normal rainbow is formed by water droplets with two internal reflections, so the rainbow's light is projected back towards the sun. In this case, the light is passed forward through the crystals, at an angle determined by their shape, so it appears to be coming from the sun's direction, but offset.
Dave Sent from my iPhone > On Aug 17, 2016, at 7:24 AM, Jackie Jones <jac...@waitrose.com> wrote: > > Dear 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 Jones > 50° 50’ 09” N 0° 07’ 40” W > > <Rainbow above sun.jpg> > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial >
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