• Question: how would you measure a water droplet in a cloud?

    Asked by holliepym to Alan, Caspar, Diana, Murray, Sarah on 21 Mar 2011 in Categories: .
    • Photo: Alan Winfield

      Alan Winfield answered on 21 Mar 2011:

      I’m afraid Hollie that I have no idea. However, I feel sure it’s something to do with ‘colloid science’. A colloid is a substance microscopically dispersed through another substance. I feel sure that the colloid scientists have figured out how to measure the size of water droplets in clouds.

    • Photo: Caspar Addyman

      Caspar Addyman answered on 21 Mar 2011:

      If you were in the cloud then you could shine a bright light through the cloud and see how gets scattered. If you are on the ground you could do the same thing using the sun as the light. but you might be too far away to find out what you wanted.

      So the third way would be measure water droplets in a cloud of steam from the kettle or from a shower and then extend your findings to apply on a bigger scale.

    • Photo: Sarah Thomas

      Sarah Thomas answered on 21 Mar 2011:

      I feel like I saw this on TV recently but I can’t remember exactly what they did. As far as I know they can use a thing called a cloud chamber to capture a bit of the cloud and then remove the air from it and then weigh the water that is left and then multiply it by the area of the cloud. Or I think there is maybe an instrument than can calculate it by shining a beam of light into the cloud and then the light gets scattered by the water droplets and then the amount of scattering is related to number of droplets.

    • Photo: Diana Drennan

      Diana Drennan answered on 21 Mar 2011:

      I would send up drones (small robotic planes without a pilot) that carried a sensor of some sort, perhaps a laser droplet analyzer like this one (http://www.oxfordlasers.com/imaging/sizing/visisizer_portable.html) and collect lots of data, then I’d want to do some statistics to see the average size of droplets. We could ask all sorts of questions then: what are the sizes at different heights within the cloud, how does the size correlate with temperature, how does the size correlate with what the precipitation is (snow, sleet, rain, hail, etc)… good question !!

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