• Question: Why is the sea blue?? :)

    Asked by madsmith98 to Anil, Blanka, Cees, Emma, Mike on 24 Jun 2012.
    • Photo: Blanka Sengerova

      Blanka Sengerova answered on 24 Jun 2012:

      I think the colour of the water is due to the selective absorption and scattering of the visible light. You’ll probably be aware that the visible light spectrum is made up of the colours ROYGBIV (red-orange-yellow-green-blue-indigo-violet) and different materials absorb or scatter different light colours (they have different wavelength) to a varied extent.

      I presume this means that the particles in the sea or large water bodies absorb or scatter the colours other than blue or green, letting these ones through and making them visible to us. But I stand to be corrected…

    • Photo: Michael Cook

      Michael Cook answered on 25 Jun 2012:

      I had no idea that was the reason! It turns out I thought it was for a completely wrong reason entirely. Thanks Blanka!

    • Photo: Emma Trantham

      Emma Trantham answered on 25 Jun 2012:

      I agree with Blanka in that the colour of water is due to absorption of some light whilst other light is reflected.

      The light rays are absorbed both by the water and by the things that are in the water (like plankton).

      When you see a blue sea it is because the water and the things in the water are absorbing the red-yellow light waves but are scattering and reflecting the blue light. It is this scattered light that gets to our eyes and so this is the colour we see.

      Edited to add: should also have said that the colour is also due in part to the water reflecting the colour of the sky

Comments