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Making clouds

  1. Oct 11, 2016 #1
    why clouds are made,even there is more space in sky?i mean the vapor,why are they in so together?
     
  2. jcsd
  3. Oct 11, 2016 #2
  4. Oct 11, 2016 #3

    davenn

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    Gold Member

    sometimes

    that link was a basic description for young school kids

    how old are you and what education?, so I can possibly give a more detailed response :smile:

    Dave
     
  5. Oct 11, 2016 #4
  6. Oct 11, 2016 #5
    ."..As the water vapor goes higher in the sky, the air gets cooler. The cooler air causes the water droplets to start to stick to things like bits of dust, ice or sea salt.
    ...The droplets are so light they float in the air. Sometimes those droplets join with other droplets. Then they turn into larger drops. When that happens, gravity causes them to fall to Earth...."

    This link is a good example of the principle that simplifications of complex subjects often produce false statements. 1) It is not the temperature of the surrounding air that cools water vapor in convection, it is the fact that molecules moving against the force of gravity lose thermal energy. 2) The cooler atmosphere does not cause condensation. Condensation would still occur in the absence of any other gases. The causes are the polar nature of the water molecule, and the physio-chemical forces that attract vapor molecules to one another and to certain particulates (condensation nuclei). 3) Cloud droplets do not "float". They are continually falling in keeping with the basic principle of gravitational attraction. It is just that their mass/cross-section ratio is so slight that their falling speed is often less than the upward speed of the surrounding convective air. Remember, the life of a cloud droplet is rarely more than a minute or two.

    As a retired professor, I fully understand that simplifications are sometimes necessary. Rather than make false statements, however, I believe that it is better to simply tell your students that the subject is too complex for their current understanding, but that it can be make clearer with further education in that topic (a 300 level course, for instance, rather than a 100 level). I have spent far too many hours telling my introductory students that what they think they know is not really supported by the current weight of scientific evidence. For example: Water does not automatically freeze at 0°C. Hot air does not automatically rise. Winds do not always blow from areas of high pressure to areas of low pressure, etcetera.
     
  7. Oct 13, 2016 #6
    thanks
     
  8. Oct 13, 2016 #7
    thanks
     
  9. Oct 13, 2016 #8
    thanks professor,i got a rough idea..
     
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