Three-armed rainbow
Post categories: weather
| 14:52 UK time, Friday, 22 October 2010
Katie Lench from Gwynedd sent in this beautiful photo of a rainbow.
Rainbows. Photo: Katie Lench
She saw this double rainbow on the A55 at Llanfairfechan yesterday. It's strange, though, because it has a third 'arm' pointing upwards. Katie has never seen a rainbow like this before and wants to know how it is formed.
To see a rainbow we need sunshine and falling rain. The main or primary rainbow is bright but outside it you can see a fainter secondary bow. The secondary bow is wider and its colours are reversed so that the reds of the two bows always face one another.
The third bow or 'arm' in the middle of the picture is called a 'reflection rainbow' and is produced by by sunlight beaming upwards after reflection from calm water - in this case from the sea.
You can read more about reflection rainbows and here on .
Another rainbow taken by Jeff Haward at Graig Coch Dam in the Elan Valley
You never know, you may see a rainbow over the weekend because a mixture of sunshine and showers are forecast. If you find a pot of gold at the end of the rainbow, remember me and send me a few coins!
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