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Relative humidity

  1. Jul 11, 2009 #1
    1. The problem statement, all variables and given/known data
    Consider the folowing statements made about the space just above a small block of ice placed in still air,where the room temperature and the relative humidity are 30 degrees and80%
    (A) Absolute humidity of air in the space just above the iceblock is higher than the absolute humidity of air away from the block
    (B) Relative humidity of air in the space just above the ice block is higher than the Relative humidity of air away from the block.
    (C) Air in the space just above the ice block is drier than the air away from the block

    which of the above statements is true
    (1) only A (2)A & B only (3)B &C only (4)A&Conly (5)A,B&C only
    2. Relevant equations



    3. The attempt at a solution

    I know that Relative humidity increases when the temperature decreases,
    as for absolute humidity ,I don't think the temperature has any effect on AH?but I'm not sure.
    I also think the temperature above the iceblock is less than its surrounding temp. so I think B would be true and maybe A?
    If B were true ,I don't think C would be true,so I think the answer is(2),but I'm very very doubtful.
    Hope someone could help.
    Thank you
     
  2. jcsd
  3. Jul 11, 2009 #2

    LowlyPion

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    Homework Helper

  4. Jul 11, 2009 #3
    Thanks so much for the link,sir.
    so when temperature decreases,the absolute humidity decreases(dew point also decreases),
    then,
    (A) would be wrong,cause the temperature above the ice block would be less than the surrounding temperature,so AH would be less here than that of the surrounding,and C would be correct for the same reasons.
    (B)would also be correct,
    so the answer is (3) B &C only?

    THANK YOU
     
  5. Jul 11, 2009 #4

    LowlyPion

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    I'd think so. Remember Absolute Humidity is the amount of water that a volume of air holds. The relative humidity is what percentage of the 100% absolute humidity is measured at a particular temperature.

    Absolute humidity is mass/volume and relative humidity is a %.

    http://en.wikipedia.org/wiki/Absolute_humidity#Absolute_humidity
     
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