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Author Topic: Why can't I see my breath when I exhale through my nose?  (Read 7645 times)

James Carrington

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James Carrington  asked the Naked Scientists:
   
Dear Chris

Love the show. I listen on my daily commute to work and at night when I go to bed via my ipod.

My question is this : why when its really cold outside, does my breath come out of my mouth as a cloud of mist, but then not when I breath out of my nose?

Thanks, keep up the great work!

James Carrington

What do you think?


 

lyner

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Why can't I see my breath when I exhale through my nose?
« Reply #1 on: 16/02/2009 18:04:17 »
When yo breathe in through your nose, I was always told that the air is warmed up a bit. So, when you breath out, it must cool down a bit as it goes through those same tubes and spaces. There must be some condensation in there which reclaims some of the water vapour.
When you breathe in and out through your mouth, this doesn't take place so you lose more water and make a huge warm cloud of water drops.
I bet this is one of the reasons why fitter runners, who  are SO COOL that they can get by with nose breathing alone, suffer much less from water loss. They don't slaver and pant away so they don't need to drink gallons of water after a race.
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #2 on: 17/02/2009 15:30:27 »
And when it gets really cold (say - 25 or so) you can see it even when you exhale through your nose. I tried.
 

lyner

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Why can't I see my breath when I exhale through my nose?
« Reply #3 on: 17/02/2009 16:35:36 »
Oh yes. It's a matter of degree - relative humidity etc.
 

Offline graham.d

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Why can't I see my breath when I exhale through my nose?
« Reply #4 on: 17/02/2009 17:44:48 »
The velocity of the air may have something to do with it too. You see your breath much more when you open your mouth and breathe out slowly. The nasal passages are quite small so the air speed is higher generally.
 

lyner

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Why can't I see my breath when I exhale through my nose?
« Reply #5 on: 17/02/2009 20:53:09 »
This could mean that the air mixes as it comes out and the average humidity would be less? A reasonable idea. If you breathed out slowly, through your nose you might get the same effect.
Is anyone in a position to make an experiment? Not suitable here.
« Last Edit: 17/02/2009 20:56:20 by sophiecentaur »
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #6 on: 18/02/2009 22:59:46 »
I will try to do this experiment tomorrow in the car. However, exhaling fast and hard through the nose has risks.

Based on memory for the moment, I would say that exhaling slowly through the nose results in not enough air to see the effect for yourself. This morning when I tried, I exhaled with medium speed and it worked fine. Vapor is clearly visible. And it was not even that cold. -5 Celsius I guess.

Will report back.
 

lyner

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Why can't I see my breath when I exhale through my nose?
« Reply #7 on: 18/02/2009 23:31:26 »
It also depends upon relative humidity.
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #8 on: 18/02/2009 23:51:34 »
It also depends upon relative humidity.

Yes, but I will not be able to measure this. I will compare airspeed to vapor formation only. Completely subjectively of course.
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #9 on: 20/02/2009 01:08:18 »
Sorry, could not test yet. Too warm today.
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #10 on: 05/03/2009 21:09:03 »
OK, I tested it. There seems to be no noticeable difference between exhaling through the nose or through the mouth in regard to water vapor. Same with exhaling harder. The harder you blow the more water vapor there is. It seems approximately proportional. It is difficult to measure this precisely. All I did was to stand in front of a mirror in a really cold room. Completely subjective, although I was surprised how much water vapor is visible even when you exhale slowly through the nose.
 

lyner

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Why can't I see my breath when I exhale through my nose?
« Reply #11 on: 05/03/2009 22:50:27 »
I bet you were so enchanted with your own image in the mirror that you forgot to pay attention to the experiment.  I have the same problem, sometimes. Is your middle name Narcissus?  [^]
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #12 on: 06/03/2009 01:26:41 »
Well, it was sort of like this until I began the part of the experiment that involved rapid and strong exhalation through the nose. It was not that much fun to look at any longer. A handkerchief took care of he mess but the image was spoiled.
 

lyner

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Why can't I see my breath when I exhale through my nose?
« Reply #13 on: 07/03/2009 13:05:01 »
Heavy breathing eh!
I need to sit down after that sort of thing.

btw, Karsten, I see on another thread that you are also into wet T shirts.
« Last Edit: 07/03/2009 13:14:21 by sophiecentaur »
 

Offline Karsten

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Why can't I see my breath when I exhale through my nose?
« Reply #14 on: 07/03/2009 14:48:34 »
btw, Karsten, I see on another thread that you are also into wet T shirts.

Depends on who is wearing them.  [:I]
 

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Why can't I see my breath when I exhale through my nose?
« Reply #14 on: 07/03/2009 14:48:34 »

 

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