Naked Science Forum

Life Sciences => The Environment => Topic started by: paul.fr on 25/03/2007 07:17:55

Title: Humidity
Post by: paul.fr on 25/03/2007 07:17:55

Often quoted in the weather forecast, but what exactly is humidity? How does it affect us, and how is it measured?

Title: Humidity
Post by: Karen W. on 25/03/2007 07:44:49

Humidity I belive is the amount of moisture in the air, how they measure it, I am not sure perhaps by the rate of evaporation LOL I really don't know..LOL LOL,Humid wet damp areas can be really tough on People with respirtory problems!

Title: Humidity
Post by: Bored chemist on 25/03/2007 13:07:29

Humididty is amount of water in the air. It's normally expressed as relative humidity which is a measure of how much water there is as a percentage of how much water the air could hold at that temperature. There are a number of ways of measuring it; the easiest is to use an electronic sensor who's electrical properties (capacitance I think)) vary as it gains and loses water from the air. The other ways are to cool the air and note the temperature at which water condenses out, this temperature is called the dew point, and to look that up in a set of tables for dew point and temperature to give relative humidity.
The tiresome but accurate way of doing it is to take a known volume of the air and pass it through something like silica gel which will remove the water. If you weigh the silica gel before and after you can find out how much water there is in the air. If you do this with the same volume of air which has been saturated by bubbling it through a bottle of water you can find out how much water the air can hold. From those you can calculate the relative humidity.
In my experience low humidity is also a problem for people with respiratory complaints and it's also uncomfortable when it dries the eyes. As with most things it's best to have a moderate humidity- what is most comfortable depends on the temperature as well as the individuals tastes.

Title: Humidity
Post by: paul.fr on 25/03/2007 16:38:42

Cheers, BC

Title: Humidity
Post by: eric l on 25/03/2007 18:47:03

Older hygrometers and (mainly) hygrographs used hair from a horses tail.  Apparently hair gets longer with increasing humidity, but this increase is not linear.

I remember a windmill where the miller had suspended a string  over the length of the ceiling.  One end was fixed, the other run over a roll and ended in a small weight.  According to the miller, the position of the weight was a good indication of humidity.  It was a wooden windmill, I am not sure wether it was the wood or the string itself that was influenced by humidity.  It is a bit far off to just go and check.

If my memory does not fail me, the electronic devices are based on changes in conductivity of semiconductor cells.
 

Title: Humidity
Post by: Karen W. on 26/03/2007 02:01:36

SO does that mean If Neily and Paul, stay in a nice humid climate that they could expect more rapid hair growth....Could this possibly thicken what little is on their cute little heads!!LOL

[size=07pt](grining and holding a nice steamy pot of water at the ready to add moisture to the air for me boys) LOL[/size]

Title: Humidity
Post by: Carolyn on 26/03/2007 03:49:18

Quote from: Karen W. on 26/03/2007 02:01:36

SO does that mean If Neily and Paul, stay in a nice humid climate that they could expect more rapid hair growth....Could this possibly thicken what little is on their cute little heads!!LOL

[size=07pt](grining and holding a nice steamy pot of water at the ready to add moisture to the air for me boys) LOL[/size]

Ohhh, hope not.  Bald is better. [;D]

Title: Humidity
Post by: Karen W. on 26/03/2007 03:55:52

I like either or they are both nice... I often wonder which feels better, you know more comfortable!!

Title: Humidity
Post by: paul.fr on 26/03/2007 04:17:34

Quote from: Carolyn on 26/03/2007 03:49:18

Quote from: Karen W. on 26/03/2007 02:01:36

SO does that mean If Neily and Paul, stay in a nice humid climate that they could expect more rapid hair growth....Could this possibly thicken what little is on their cute little heads!!LOL

[size=07pt](grining and holding a nice steamy pot of water at the ready to add moisture to the air for me boys) LOL[/size]

Ohhh, hope not.  Bald is better. [;D]

[;D]  [;D]  [;D]

Title: Humidity
Post by: Karen W. on 26/03/2007 04:27:59

lol

Title: Humidity
Post by: moonfire on 26/03/2007 14:40:57

Quote from: Carolyn on 26/03/2007 03:49:18

Quote from: Karen W. on 26/03/2007 02:01:36

SO does that mean If Neily and Paul, stay in a nice humid climate that they could expect more rapid hair growth....Could this possibly thicken what little is on their cute little heads!!LOL

[size=07pt](grining and holding a nice steamy pot of water at the ready to add moisture to the air for me boys) LOL[/size]

Ohhh, hope not.  Bald is better. [;D]

I know how you love bald men!  LOL

Title: Humidity
Post by: neilep on 26/03/2007 16:25:00

I am bald....down there !!

Title: Humidity
Post by: Carolyn on 26/03/2007 16:42:01

Quote from: moonfire on 26/03/2007 14:40:57

Quote from: Carolyn on 26/03/2007 03:49:18

Quote from: Karen W. on 26/03/2007 02:01:36

SO does that mean If Neily and Paul, stay in a nice humid climate that they could expect more rapid hair growth....Could this possibly thicken what little is on their cute little heads!!LOL

[size=07pt](grining and holding a nice steamy pot of water at the ready to add moisture to the air for me boys) LOL[/size]

Ohhh, hope not.  Bald is better. [;D]

I know how you love bald men!  LOL

You betcha!!! Always have, always will!!!  [::)] [;D] 

Now, I'll try to stop thinking of bald men so we can get this thread back on topic. [;)] [;D]

Title: Humidity
Post by: Karen W. on 26/03/2007 16:53:56

Quote from: neilep on 26/03/2007 16:25:00

I am bald....down there !!

LOL, I won't say what just came to mind as I am too much of a lady!! LOL!!!