• Question: What causes a rainbow?

    Asked by smithmoorebell to Ben, Clare, Ezzy, Mario, Sam on 15 Mar 2012.
    • Photo: Clare Burrage

      Clare Burrage answered on 14 Mar 2012:

      The white light that comes from the sun, and from our lights and lamps is really a mixture of light of lots of different colours. You can split up white light into all of its different colours using a prism (triangle) of glass. There’s a picture of it here

      This is because different colours of light travel at different speeds in glass.

      The different colours of light also travel at different speeds in water, and raindrops can also act like water to split the white light from the sun up into its different colours, this is what makes the colours of the rainbow.
      The light from the sun actually bounces off the back of the raindrop back towards us, which is why you’ll only ever see a rainbow when you have your back to the Sun. All of the raindrops in the air will be spliting light into it’s different colours, but only a few of them reflect that coloured light back towards us. The raindrops that can do this form an arc on the sky, and that’s why we see a rainbow.

    • Photo: Elizabeth Pearson

      Elizabeth Pearson answered on 15 Mar 2012:

      When raindrops are falling they look more like spheres than raindrop shapes. The light comes through them and the raindrop acts like a prism made of water, splitting the light into a spectrum, or rainbow. when it rains there are thousands of raindrops all doing this so we can see it from a distance. It looks like an arc because of the shape of the raiindrops.

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