• Question: How are clouds formed

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      Asked by Owen:-) to Andy, Chris, Harriet, Jess, Nikki on 11 Mar 2016.
      • Photo: Harriet Reid

        Harriet Reid answered on 11 Mar 2016:

        Water evaporates from the ocean, (and rivers ext too but mostly the ocean). As it rises it cools, and turns from a gas into tiny liquid water drops. Clouds are formed from the tiny drops of water. its the same as when you can see your breath on a cold day. The water gas in your breath cools and forms small clouds.

      • Photo: Christopher Blanford

        Christopher Blanford answered on 11 Mar 2016:

        Hi again, Owen 🙂

        What’s interesting with that is that when the water gas makes clouds, it gets off heat and raises the temperature around that level. And it doesn’t always get colder and colder as you get higher up. So you end up with layers of clouds, like you can see from a plane window.

        Chris

      • Photo: andy chapman

        andy chapman answered on 13 Mar 2016:

        They may all just be collection of water vapour but the diversity of formations is amazing. Check out these pics of my favourite type of cloud:

        http://www.bbc.co.uk/earth/story/20150716-nine-rare-and-beautiful-clouds

        The Kelvin-Helmholtz wave.

        One that never bores me is not really ‘natural’ but still a sort of cloud. The contrail (white stripe of cloud) that forms behind an aeroplane. This is a never ending reminder to me of a wonderful process in chemistry called ‘nucleation and growth’

        The blue sky up there is supersaturated with water in the gas phase (no more room for any more single molecules of water top float about as individual molecules). However, for a beautiful reason I won’t go into here (it is pretty complicated, and maths is the easiest way to show it), these individual molecules of water (which are invisible to us as they are two small and cannot reflect and scatter visible light) cannot clump together to form a droplet of liquid water (which becomes visible to us because it is now large enough to visible reflect an scatter light) on their own. The want to do this very badly but this will only happen is a tiny particle of something, dust, grit…whatever starts off the process. This little particle of something (the nucleus), nucleates (or starts off) the process of water droplet growth.

        Take one of those hand warming gel packs you have to snap to start off the heating. This is supersaturated sodium acetate solution – the dissolved individual molecules of sodium acetate would love to be solid sodium acetate crystals (you can tell they would love it because so much heat is give out when they do), but they can’t until you provide a ‘nucleation’ event by snapping the little metal disk in it. You can watch the crystals grow from this initial nucleation. There are some very cool videos of this on you tube:

        I am sure your teacher would be happy to show you this………(sorry sir/miss)

      • Photo: Jessica Groppi

        Jessica Groppi answered on 13 Mar 2016:

        Hi!

        The formation of the clouds is part of the cycle of water: water evaporates and through air currents reaches high altitudes. Variations of pressure and temperature in the atmosphere cause the water vapour to condense to form these masses where water is mixed with air.

        Jess

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