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Effect of rain on velocity of sound

  1. Jun 4, 2014 #1
    I was suddenly asked this question by a friend...

    How a 'cats & dogs' rain would affect the velocity of sound through air?(as we know velocity of sound through water is five times than in air)

    I just couldn't be sure how to answer it... The raindrops are really small but there's a lot of them there... How big the effect could be?
     
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  3. Jun 4, 2014 #2

    phinds

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    I doubt it changes the velocity at all unless there's mist accompanying the rain. What it DOES change is the amount of sound that propagates over a given distance.
     
  4. Jun 4, 2014 #3

    AlephZero

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    The speed of sound depends mainly on temperature, but also on the humidity of the air. The sensitivity of the speed to humidity is also temperature dependent, which is not surprising since the fraction of water vapor in the air at "100% humidity" is very different at 0°C and 100°C. There is a graph here: http://www.phy.mtu.edu/~suits/SpeedofSound.html

    The basic cause is the change in average molecular weight of the air. The MW of dry air is about 29, but the MW of water vapor is only 18.

    As phinds said, the liquid raindrops don't have much effect on the speed of sound, but they scatter and absorb the sound waves.
     
    Last edited: Jun 4, 2014
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