Rainbow upside down

The upside-down rainbow, a rare natural phenomenon, appeared in the English city of Cambridge over the weekend.

Astronomer Jacqueline Mitton in Cambridge captured a beautiful image around 445 local time on Sunday, September 14. An arc - looking like a rainbow upside down, was 'exposed' in the sky of the city.

'This year is 60 years old but I have never seen the same phenomenon before. It's an interesting combination of factors that happen at the same time, ' said Mrs. Mitton.

A rainbow is a dispersion of light from the sun when refracted and reflected through raindrops. But the upside-down rainbow appears when sunlight is refracted through ice crystals on high-level clouds. This phenomenon usually only occurs in cold areas.

Astronomer Mitton said: 'The condition for a rainbow to be upside down is: there must be ice crystals and the sky is really blue.'

'It is surprising that the phenomenon is "showing up" at a place like Cambridge, because normally it only happens in cold areas.'