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Asked by puggy4 to Angus, Christian, Hannah, Laura, Simon on 20 Jun 2013. This question was also asked by beccawilko.
Question: how are rainbows made?
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Laura Roberts Artal answered on 20 Jun 2013:
Rainbows appear when there are raindrops in the atmosphere. When rain drops reflect white light from the sun, they break the ray of light into all the colours of the rainbow. You actually need lots of rain droplets in the atmosphere to be able to see all the different colours.
Did you know rainbows always form in the sky opposite to that of where the sun is?
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Angus Ferraro answered on 20 Jun 2013:
Light is made up of different colours, but we don’t normally see them because they’re all mixed together. Some things – like prisms – can split light up. Prisms bend (‘refract’, technically) rays of light, and some colours bend more than others, so different colours get split up.
If the Sun shines at the right angle through raindrops, some light goes inside, bounces off the back of a raindrop and comes back towards us. The raindrop, just like a prism, bends the light and splits it into all of those beautiful colours. The raindrops need to be a certain size for this. The droplets of water in clouds are far too small.
So why is it bow-shaped? Well, the angle at which the light bounces off the inside of the raindrop needs to be just right. The Sun needs to be behind us. The sunlight goes past us and hits the raindrop. But the angle at which some of the light bounces off is about 42 degrees. That’s why, when you face a rainbow, the coloured light is coming towards you at an angle of 42 degrees. The Sunlight straight ahead (0 degrees) can’t bounce off the inside of the raindrop.
Hope that makes sense – it’s actually quite complicated and difficult to get your head round!
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Comments
puggy4 commented on :
thank you!