• Question: why does the shower room steam when the water is not 100 degreees so theoretically can't evaporate?

    Asked by beaw to Ben, Jony, Katharine, Mark, Peter on 19 Nov 2011.
    • Photo: Ben Still

      Ben Still answered on 17 Nov 2011:

      100 degrees C is need to boil water but evaporation happens all the time – some water molecules get jostled around enough from random movements of those molecules around them that they have enough energy to escape the rest and become vapour.

    • Photo: Mark Basham

      Mark Basham answered on 17 Nov 2011:

      In fact steam is invisible, what we see is tiny droplets of liquid water which have cooled enough to become liquid again, its like having a miniature cloud in your bathroom 🙂

    • Photo: Katharine Schofield

      Katharine Schofield answered on 17 Nov 2011:

      I stayed in a hotel once where there was a heated section of the shower room mirror so the water droplets didn’t condense on that bit of the mirror. Now that was smart thinking. Must get one of those one day…

    • Photo: Peter Williams

      Peter Williams answered on 19 Nov 2011:

      Evaporation can happen at any temperature. Look up the triple point of water – this is when ice, liquid water and vapour co-exist. If you come to our lab we have a demonstration bell jar where we can evacuate the air and take a plate of water down to the triple point – it boils and freezes at the same time!

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