• Question: Why are clouds grey when it is going to rain and white normally?

    Asked by bexh96 to Donna, Jo, Mark, Stuart, Tim on 24 Jun 2010 in Categories: .
    • Photo: Donna MacCallum

      Donna MacCallum answered on 22 Jun 2010:


      Great question! It’s all about the amount of water vapour contained in the clouds and how it refracts light (changing the colour) – more water = greyer clouds. I prefer the white ones!

    • Photo: Joanna Buckley

      Joanna Buckley answered on 22 Jun 2010:


      Good question, bexh96!

      Basically, clouds look gray when they block sunlight. The thicker the cloud, the more light it blocks. They’re thicker when it’s going to rain because there more water vapour in them ready and waiting to be deposited as rain. 🙂

    • Photo: Tim Craggs

      Tim Craggs answered on 24 Jun 2010:


      I think it is to do with the density of the water vapour. When it is about to rain, the cloud is totally saturated, so it can’t actually take any more water, and looks darker. That is when it is time to run for cover!

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