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Releasing air from mouth

  1. Jul 31, 2014 #1
    Whay is it that when we release air from our mouth when it is little open then the cold air is released but when we release air from large open mouth hot air is released.
     
  2. jcsd
  3. Jul 31, 2014 #2

    A.T.

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    The thinner faster stream pulls more cold air from surroundings with it.
     
  4. Jul 31, 2014 #3

    adjacent

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    I can release hot air even when it is opened very little. I think you meant opened little and blowing fast.
     
  5. Jul 31, 2014 #4
    Releasin air from mouth

    Ya you are correct
     
  6. Aug 1, 2014 #5
    I think that you will find that the air coming from your mouth has the same temperature as it had in your mouth regardless of the speed of the stream. The difference is in the effect on a damp surface. The amount of evaporative cooling that takes place on that surface is in direct proportion to the square of the wind velocity
     
  7. Aug 2, 2014 #6

    A.T.

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    That's true, but I think it's mostly what I said in post #2. When put your finger close to the mouth, then a thin fast stream still feels warm. When you move the finger away it becomes colder, because more cool air is pulled with the stream.
     
  8. Aug 2, 2014 #7
    It's 105°F (about 41°C) here right now. Where's the cool air coming from?
     
  9. Aug 2, 2014 #8

    A.T.

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    In this case it's not about being colder, but about having less humidity. You breath has 100% relative humidity, so it cannot evaporate the sweat from your finger, no matter how fast you blow. To feel cold the stream must pull with it some less humid air from the surroundings.
     
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