• Question: What makes a rainbow?

    Asked by 942ntrd27 to Uday, NULL, Pierre, Irene, Chloe on 9 Nov 2015. This question was also asked by mylastlife.
    • Photo: Uday Bangavadi

      Uday Bangavadi answered on 9 Nov 2015:


      Rainbow is formed due to a scientific phenomenon called dispersion of light. When there is rain and sun together the light from sun is dispersed by water droplets which causes rainbow.

      Dispersion is a process of splitting white light into its fundamental colours.

      Its the same process observed when white light is passed into a prism the white light is split into different colours. Here the water droplets acts as prism.

    • Photo: Irene Regan

      Irene Regan answered on 9 Nov 2015:


    • Photo: NULL

      NULL answered on 9 Nov 2015:


      Light from the sun is actually lots of colours. The sun is so bright that they all mix and look white (or maybe yellow-ish), but in fact the sun shines in all colours.

      You don’t notice the colours until they happen to pass through something thicker than air, like glass or water, with a bit of an angle on it. When that happens, the light gets “dispersed”. Some colours of light tend to move slower than others, so they end up separated. And we see that as a rainbow.

    • Photo: Pierre Casaubielh

      Pierre Casaubielh answered on 9 Nov 2015:


      The light coming from the sun is made of many colours. Some can be directly observed from our own eyes (the “visible” light, which include: Red, orange, yellow, green, blue, indigo, violet); the rest cannot be directly observed and require light sensors and/or filters.

      Light can be reflected, transmitted and scattered by elements. Water droplets are “transparent”, and light can pass through the droplets and be reflected at their surface…. and scattered. The way that the light is scattered is done at a specific angle (this angle is made considering the arrangement: source of light – water droplets (raining wat) – observer).
      Then, if A RED light and a GREEN light are illuminating in the same direction the water droplets, someone should be able to see green and red colour touch on the water droplets cloud.
      The colours of the visible light will be scattered at different angle and this is observed in the rainbow.

      A rainbow requires it is “raining somewhere” and someone is there at the right moment. On a final remark, two people being far away won’t be able to see the same rainbow.

      There are plenty of rainbows in Ireland; next time you see one, call your friends to see if they see one 😉

    • Photo: Chloe Huseyin

      Chloe Huseyin answered on 17 Nov 2015:


      I think the other scientists have answered this really well already, so I found these pictures to help illustrate what they said:

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