Saw this circumzenithal arc on Friday 15th from Abingdon. Looks much like an upside down rainbow above the sun (which needs to be lower than 33 degrees or so for this to occur) – it occurs due to horizontally orientated ice crystals high in the upper atmosphere.
Only had the camera on my phone so the image is a bit ropey, but hopefully clear enough…
Circumzenithal Arc by Graeme Coates is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.