We visited Broadway Tower, a unique Folly Tower built on the second highest point on the Cotswold hills, a couple of weeks ago. On a clear day you can see a huge 62 mile radius encompassing up to 16 counties. While we were there, on looking up we realised there was a 'smile in the sky' above us. The circumzenithal arc, which looks similar to a rainbow, is caused by the refraction of sunlight through ice crystals, usually in cirrus or cirrostratus clouds. Apparently these are more common than rainbows, but presumably due to their smaller size and higher position, they are seen more rarely.
Smile in the sky enjoyed by Naomi at cotswoldfamilyholidays.com