Original text from blog of Emiko Numauchi (Numayu) in Minamisoma City 08.06.2012
The rainbow makes an inverse circle.
It have been sunny everyday and it didn't rain.
Was it because of there were a lot of moisture vapor above in the sky?
It was a half rainbow surrounding the sun.
From the theory of the rainbow, the one my father saw was because of there's a lot of moistures above in the sky and it was drew as if it surrounded the sun and my father's viewing location was just below it.
Courtesy : Emiko Numauchi