why does dry heat take away humidity?

Discussion in 'Chemistry' started by river, Oct 17, 2011.

  1. river Valued Senior Member

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    for instance if I use a baseboard heater it takes Humidity out of the air of a room

    why ?
     
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  3. Me-Ki-Gal Banned Banned

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    Your testing Me . Lets see if this is right . I might have it backwards . Moister moves hot to cold , or is it cold to hot( Hot to cold I am pretty sure . How does an evaporation air conditioning work ? It takes the moisture out of the air and that cools the space . Heat is a moister sink if you think about it . I think that is right . I gave that shit up so My mind is having trouble with recall on this matter . Fuck Business . I play music now instead of working building . No I won't look it up either to verify what I said . I got the book that explains it on my messy desk here some place .

    O.K. if I am wrong someone else will give better answer
     
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  5. arauca Banned Banned

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    There can also be thought that moisture in air is a water aggregate as the temperature rise a higher collision rate and the water aggregate decrease and disperse trough the volume of the house ?
     
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  7. river Valued Senior Member

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    what is " disperse trough " ?
     
  8. river Valued Senior Member

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    me-ki , hello , this is NOT a flow through situation , air conditioning

    this is about a room with a baseboard heater taking the humidity OUT of the room somehow

    how ?
     
  9. billvon Valued Senior Member

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    It does not. The amount of water in the air stays exactly the same. But the RELATIVE humidity goes down, since warm air can hold more water - so 100% humidity at 50F means much less water total than 100% humidity at 100F.
     
  10. cosmictraveler Be kind to yourself always. Valued Senior Member

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    If your heating the air in a room that air is already low in moisture content already being that it is cold. The recommended average relative humidity level is between 35% and 45%.During cold winters, your heating system can make the air in your home too dry, making it uncomfortable for you. It can also cause wooden items to crack. To improve the air quality, you can add a humidifier to those areas where you spend the most time, or you can install a whole house humidifier to your heating system.

    In the summer when you are not heating, depending on the climate in your area, there may be too much moisture in your home, which can cause damaging mildew. To control this moisture, you need a dehumidifier.

    WIKI
     
  11. origin Trump is the best argument against a democracy. Valued Senior Member

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    It is because of relative humidity. The amount of moisture that the air can hold is dependent on the temprature of the air. This means that at 100F you will have a lot more grams of water per cubic meter of air than with a temperatrue or 50F for the same relative humidity. At 100% humidity you will start to have the moisture in the air condense on surfaces (dew for instance). Dew forms in the morings because it is colder (usually) and so even though the amount of water in the air didn't change the colder air goes above 100% relative humidity only because of the temperature change.


    So what does this mean? Lets assume that the RH is 50% outside and the temperature is 45F. In your heated house the temperature is 68F, that means that the RH in you house will be less, maybe 20% because the temperature is higher (not really sure if the number is 20%, I don't feel like looking it up or calculating it - but you get the point).
     
  12. arauca Banned Banned

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    The size of the water particles . the air and vapor in the aie collide and break down into finer mist
     
  13. billvon Valued Senior Member

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    Water vapor is already 'dissolved' at the molecular level in air. Relative humidity describes this dissolved water. Mist is not accounted for in relative humidity. (Which makes sense - otherwise misty air would be greater than 100% humid.)
     
  14. arauca Banned Banned

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    Are you sure . In the air we have a partial pressure of air and water, as the water content in the air increases the humidity increases . Now the moisture in the air is not on molecular level bit on fine mist as the temperature increase the particle size decrease due to kinetic collision and so the total content of gaseous material decrease.

    In case of the moist air which you probably refer is when the particle get large enough then you have rain. and then you have 100 % rel humidity
     
  15. billvon Valued Senior Member

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    Water vapor is gaseous water. It is not a mist of liquid particles. It is an invisible gas.

    Mist, on the other hand, is a bunch of drops of liquid water.
     
  16. Me-Ki-Gal Banned Banned

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    It collects at the windows . Hot to cold and your windows are the weak spot in insulation value so the moisture mitigates toward the windows and doors . When you open the door you allow it to escape into the cold out doors and it drys out the house popcorn fart dry . It moves from hot to cold . So it sucks it out of the air and condensates at your windows . Go look at your window and see for your self . Another place is right above the electric base board heater that is typically under a window and an exterior wall . Why is it discolored Like that you might ask your self . Condensation from the temperature extremes colliding would be my guess. Hot to cold .

    Every time you open your door in the winter you dry out the air in your house because of it . Also around here even on a heavy snow day the exterior air is extremely dry . The snow has very little moisture in it . It feels like high humidity some times but it is more of the cold that makes you feel that way . When the cold air warms up in your house ? It turns popcorn fart dry to the point your skin will get all the moisture sucked out of it . Extra moisturized bath Soap is my suggestion or boil a pot of water . Humidifiers work good too . Just remember what you put in will more than likely collect at the windows and could possibly mold
     
  17. Fraggle Rocker Staff Member

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    Your windows (assuming they are not double-paned) are in contact with the cold outdoor air on one side and the warm indoor air on the other. By convection, the glass reaches a temperature that is very roughly midway between the indoor and outdoor temperature. This extremely cold object on the boundary of your artificially heated room causes (by radiation and convection) the air very close to it to become colder than the rest of the air in the room. As explained in the preceding posts, cold air cannot contain as much evaporated water as warm air, so unless the room is very dry some of the water liquefies and sticks to the glass.

    This is one of the reasons for rain. As the air in the higher level of the atmosphere cools due to weather patterns, some of the water that it contains is expelled. It may be able to exist as vapor for a while (if it's at ground level we call it "fog," if it's above us we call it "clouds"), but when it becomes too thick and heavy it liquefies and "precipitates," i.e., falls down as rain.
     
  18. arauca Banned Banned

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    Is that water gas of molecular wt 18 is it 36. is it 54 ........180
    the point I am attempting to make , water as you distill is a dimer form.

    Tell me do you see bacteria floating in the air of course no.
     
  19. origin Trump is the best argument against a democracy. Valued Senior Member

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    Water is an material that has 3 phases solid, liquid and gas under normal conditions. When we talk of a 50% relative humidity that means that the water in the air is in the gas phase. This means that the water molecules are moving in the air indepedent of each other. When the relative humidity reaches 100% the water molecules will begin to clump together and form droplets (condensation).

    Here is a pretty darn good overview of humidity.
     
  20. Believe Happy medium Valued Senior Member

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  21. arauca Banned Banned

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    The water dimer is a hotly studied topic in Physical Chemistry for several reasons. (H2O)2 is thought to play a significant role in many atmospheric processes, including acid rain formation, absorption of excess solar radiation, condensation of water droplets,
    http://en.wikipedia.org/wiki/Water_dimer


    Mu example about bacteria was misunderstood, I know bacteria is involved in rain drop formation ,
     
  22. Aqueous Id flat Earth skeptic Valued Senior Member

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    As temp increases the density decreases.
     
  23. kwhilborn Banned Banned

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    I liked billvons answer in post 6 the best.

    Heating air increases the amount of vapour air can hold. So if the relative humidity is at 60%, and you double the airs capacity to hold water with heat, the relative humidity is cut in half to 30%

    Fraggle Rocker gave a good principle on how an air conditioner works. The window/refrigerator coils condense the nearby vapor into water and suck it out of the air.
     

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