Humidity

Eugene Silberstein 3

Aren't you the philosopher today?

Barrington White

Humidity

If the hotter air gets the more moisture it can hold, how come hot air is usually dry and needs to be moisturized?

bill_61

humidity is a constant...think of it as water in a glass. you have a small glass that is half full of water, the small glass representing cold air that is half full of moisture. now dump that glass of water into a big glass (hotter air) and you no longer have a half full glass of water.

the moisture outside in the wintertime varies( as does everything that mother nature creates) but once that moisture infiltrates a house, it then mixes with much hotter air. the small glass just got dumped into the big glass....................

believe it or not, someone once told me that analogy while i was in military tech school and the all too confusing psychrometric charts finally made a bit more sense to me

Eugene Silberstein 3

Heated air

As air is heated, the ability of the air to hold moisture increases.

Let's say that one pound of air has the ability to hold 118 grains of moisture at standard conditions (7,000 grains = 1 pound). Let's also say that this one pound of air is actually holding 118 grains of moisture. This one pound of air is completely saturated and cannot hold any more moisture.

The ABSOLUTE humidity of this one pound of air is 118 grains of moisture, as this is the actual amount of moisture in the air.

The RELATIVE humidity for this air sample is given by the following:

R.H. = Amount of moisture in the air sample divided by the total amount of moisture that can be held by the same air sample. This fraction is then multiplied by 100 to give the relative humidity expressed as a percent.

In the example mentioned above, the air sample held 118 grains of moisture and the total amount of moisture that the sample can hold is also 118 grains. The relative humidity is therefore (118/118) x 100 = 1 x 100 = 100%.

As air is heated, the ABSOLUTE humidity remains the same, but the ability of the air to hold moisture increases.

Let's say we heat the air sample, so that it can now hold a maximum of 236 grains of moisture. The absolute humidity is still at 118 grains. The relative humidity is therefore (118/236) x 100 = 0.5 x 100 = 50%.

Therefore, as air is heated, the relative humidity drops. During the heating season we often need humidification to help bring the relative humidity back up...

Contrary to popular belief, heating air does not remove moisture, as the absolute humidity remains the same. The fact is that the relative humidity is dropping and "drying" out the air, so to speak.

See you in class, Barrington.

don_160

you have

to keep in mind that air and water made be together but they never can hookup.

lets say air is she and,he's the water.As she gets hotter,he trying to play catchup and saturated her with more kisses.

Now has she cools down,he's now began to over whelm her and she say you're smothering me,and kicks him out of bed.

Being she'and he are always together they are always on the up and down,so the pastor has to step in and try to control them with love and care.

But the pour pastor has his hands full,because he as so many other things that infunence them,like density,people,
pressure,yadda yadda.

Just who is this pastor anyway?

don_161

I like

to think of it as air being she and,he being water they like to get together but can never hookup.

Always a conflict,then all other influence sure dont help either.

Eugene Silberstein 3

Humidity is Constant? Yes and No

Bill,

I like the analogy...

Just be sure to keep your ducts (ducks) in line when referring to humidity, which can be confusing at times.

In a given environment over a relatively short period of time, it is safe to say that ABSOLUTE HUMIDITY remains cosntant. Such is not the case with relative humidity.



Please refer to my post earlier in this thread.