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Author: Subject: What is relative humidity in human breath?
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[*] posted on 20-2-2012 at 03:49
What is relative humidity in human breath?

What is relative humidity in human breath?
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[*] posted on 20-2-2012 at 06:52

The air we exhale is saturated with water, as can be seen by "cloud formation" in the slightest drop in temperature/pressure at the moment of exhalation (with a closed mouth/nose build up pressure by exhaling and then suddenly release the air, you can see a "cloud" if you are lucky, it helps to watch in an a mirror).

A significant amount of water is lost due to breathing, and in very dry hot air you can feel this effect quite good, up to the point of almost unbearable (sleeping infront of a fireplace inside a cabin with -30 degrees Celsius outside will dry your mucus membranes to crisp, helps if you are passed out drunk as I did a couple of times..)

As a conclusion, the relative moisture in human breath is 100%.

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[*] posted on 22-2-2012 at 19:42

That's a tricky question, because one could define human breath itself as being 100% the moisture we exhale, as bahamuth has basically said.

What is the relative humidity of the air surrounding the human breath? Let me know if you can figure that one out lol. The relative humidity of breath is a constant's the relative humidity of a space surrounding the breath that changes.

That would be similar to asking, 'what is the concentration of H20 in boiling water vapors?' It's a constant 55.55M.
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[*] posted on 15-3-2012 at 05:16

RH(relative humidity) is defined as the % humidity of saturated air. aka % of the maximum humidity. It changes with temp. Humans breath out air at human body temp and it is saturated. So breath is 100% RH

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[*] posted on 26-3-2012 at 01:20

The relative humidity of the human breath (yes, almost 37 °C) is 100%. The air that gets into the lungs is divided into a huge number of tiny alveoli that are wet in order to function properly. Air moisturizing in the lungs is extremely efficient because of the huge surface area of the tissue.

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