Fire Rainbow

来源: 作舟于 2012-08-15 10:13:39 [档案] [博客] [旧帖] [给我悄悄话] 本文已被阅读：次 (6400 bytes)

Looking up into the night sky, a stunned photographer realised he had seen something special when he captured these amazing pictures.

What perhaps looks like a multi-coloured flying saucer is in fact a rare weather phenomenon known as a 'fire rainbow cloud'.

The series of photographs were taken by Ken Rotberg as the cloud hovered over south Florida, America. Mr Rotberg had just returned home from a game of tennis when he saw the odd sight as the sun dropped behind a storm cloud near Delray Beach in the early evening.

Burning bright: The rare phenomenon appeared behind a storm cloud near Delray Beach, Florida

The 49-year-old said: 'I grabbed my camera and headed out. It didn't take long for the small 'blob' of a cloud to take on some colour.

'Then the saucers appeared. I got a little excited. Then it turns out to be something just amazing.

'I was just amazed at what I was witnessing, watching it slowly change. I'm shooting this truly rare and amazing sight, shot after shot and I realise there is nobody else around me.'

'At least when I tell the story, people will believe me because I have so many pictures.'

Atmospheric optics expert Dr Les Cowley said 'fire rainbow cloud' was not the best way to describe the phenomenon, which is also known by its proper name of circumhorizon arc.

He said: 'To be blunt, it is a very silly and misleading name. The arc is not a rainbow and has nothing to do with fire.

'What is happening here is that on sunny afternoons, cumulus clouds boil upwards, pushing layers of moist air above them even higher where they cool and condense to form cloud caps or 'pileus' (Latin for cap).

'When pileus clouds form very quickly, their water droplets tend to be all the same size, the perfect condition for irridescent colours.'