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| Dennis... |
 Posted: Sun Jul 05, 2009 4:52 am |
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Does the temperature being less than freezing point (0 Celcius) have an
effect on humidity?
Assuming an air pressure close to normal atmospheric, I imagine any airborn
moisture would become ice at 0C, therefore RH would fall to 0%.
Is this correct? |
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| Robert Copcutt... |
| Posted: Sun Jul 05, 2009 7:40 am |
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Dennis wrote:
[quote:a90bb0f88f]Does the temperature being less than freezing point (0 Celcius) have an
effect on humidity?
[/quote:a90bb0f88f]
All temperature changes have an effect.
[quote:a90bb0f88f]
Assuming an air pressure close to normal atmospheric, I imagine any airborn
moisture would become ice at 0C, therefore RH would fall to 0%.
Is this correct?
[/quote:a90bb0f88f]
No.
Relative humidity = (amount of water actually in the air)/(amount of
water in saturated air).
Amount of water in saturated air = (vapour pressure of
water)/(atmospheric pressure).
The vapour pressure of water decreases with decreasing temperature but
never gets to zero.
See http://en.wikipedia.org/wiki/Water_vapor. |
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| Dennis... |
| Posted: Sun Jul 05, 2009 8:01 am |
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"Robert Copcutt" <rob at (no spam) donotspam.com> wrote in message
news:4324m.7115$1l2.5894 at (no spam) newsfe23.ams2...
[quote:c8ca458722]Dennis wrote:
Does the temperature being less than freezing point (0 Celcius) have an
effect on humidity?
All temperature changes have an effect.
Assuming an air pressure close to normal atmospheric, I imagine any
airborn moisture would become ice at 0C, therefore RH would fall to 0%.
Is this correct?
No.
Relative humidity = (amount of water actually in the air)/(amount of water
in saturated air).
Amount of water in saturated air = (vapour pressure of water)/(atmospheric
pressure).
The vapour pressure of water decreases with decreasing temperature but
never gets to zero.
See http://en.wikipedia.org/wiki/Water_vapor.
[/quote:c8ca458722]
Thanks for the reply Robert. It makes more sense having had a look at the
wiki reference. |
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