• Question: HOW DO RAINBOWS FORM

    Asked by jean520know on 22 Oct 2024.
    • Photo: Ryan Durnall

      Ryan Durnall answered on 22 Oct 2024:

      Brilliant question! Rainbows are actually really cool and are caused by something called refraction, which is a fancy word for saying that the light is bending and splitting.

      We often see rainbows when we have rain showers but it’s also sunny. That’s because the sunlight is shining through the water droplets. The droplets bend the sun’s light and splits it into 7 different colours and this is what we see as a rainbow.

      Do you know what the 7 colours are that we can see in a rainbow?

Comments

  • Photo: Andrew M

    Andrew M commented on :

    They are fascinating. Because the properties of sea water are slightly different from fresh water, rainbows caused by the salt spray of sea water on windy days are smaller than rainbows caused by rain droplets or waterfall spray.
    There’s also Moonbows caused by moonlight rather than sunlight. I’d love to see one but never have.
    I have, though, seen a straight rainbow. The sun and the edge of a cloud were at just the right angles giving the impression of a band of rainbow colour running along the edge of the cloud.

  • Photo: dave

    dave commented on :

    im not a scientist but i think its refraction of light from the sun as it passes through water

  • Photo: martinmcmahon

    martinmcmahon commented on :

    This is a questions that used to drive me crazy thinking about it when I was younger.

    When sunlight enters a raindrop, it is bent (refracted) and spreads out into its separate colours. Each colour bends by a different amount due to its wavelength. For example, red light bends less than violet light which bends the most. That’s why these two colours are on either side of the rainbow.

    But the sunlight is being bent in every single drop of water, and the crazy thing is that you only see one colour from each drop. This is because of the exact angle of the light coming out of the drop to where you are standing matches just one of the colours being bent as it spreads out. So the red light from one drop and the violet light from another drop reach your eye from slightly different angles.

    This then means that the rainbow appears as bands of colour because millions and millions of drops of rain are all bending the light at the same time. So each drop contributes to just a single colour in the overall arc from where you can see it.