• Question: Why is the sky blue?

    Asked by Cerys to Clare, Glafkos, Paul on 18 Mar 2015.
    • Photo: anon

      anon answered on 18 Mar 2015:

      Light is made up of different colours, so when sunlight reaches earth sunlight will be scattered in all directions by the particles and gases in the air. Blue light is scattered more than any colour because of its smaller waves

      But if you notice when you look at the horizon the sky will fade to light blue. The light reaching you from low in the sky passes through even more air than the sunlight reaching us from above. The air molecules have scattered and rescattered the blue light so many times and in many directions and the surface of earth has reflected and scattered the light. All this scattering mixes the colours together so we more white and less blue.

    • Photo: Glafkos Havariyoun

      Glafkos Havariyoun answered on 18 Mar 2015:

      The same reason you see a strawberry as red. Every object selectively absorbs/scatter light (which contains all colours) ! This selective absorption of water depends on the particles density and structure! Depending on the amount of scattering and absorption from the material you will see different colours!

      Air particles in the sky happen t0 scatter the blue section of light.

      You could actually do this test in a laboratory if you had a source of light and prisms of various densities!

    • Photo: Paul Booker

      Paul Booker answered on 19 Mar 2015:

      This one has been expertly answered by my esteemed colleagues already! Just keep in mind that the sky isn’t empty (it’s full of air) and that sunlight bounces of the air particles.

      Also, when the sun sets, you get more red light because it’s scattered the least, so we get that particular colour for longer as the sun goes down!

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