Re: Why does condensation end up under the table?

Hi, Karlyn!

My name is Karl, so obviously, I love your name.

I like your question a lot, because it shows you have an inquisitive mind 
and ask questions, instead of just accepting things as fact. I also like 
it because I think you are going to learn a lot more than you expected! 
You are going to learn some very important facts about weather, and a (not 
terribly important; but still fun) fact about glass, plus a few terms you 
probably have not had occasion to use. 

But, first things first: The water you see on the underside of the table 
did not come through the glass table top. This is pretty easy to prove. 
Fill a glass with cold water, and add 1 or 2 drops of a food coloring; 
mixing well. You pick the color. Now add a few ice cubes to the colored 
water. This will speed up the process of CONDENSATION. After a few 
minutes, you should see small droplets of water on the outside of the 
glass. Wipe it with a tissue and examine the color. What? No color? Good! 
That proves that the water didn't come from inside the glass. (If your 
tissue DOES show color, better throw that glass away - it's probably 
cracked.)

So where did the water come from? It came from the air. There is always 
some  WATER VAPOR present in the air. The amount of water vapor the air 
can hold is based several factors like the air temperature and the 
ATMOSPHERIC(BAROMETRIC)pressure of the air. The higher the temperature, 
the more water vapor it can hold. Conversely, the colder the air, the less 
it can hold. Back to the water glass - The glass you set on the table 
contains a cold liquid and makes the outside surface of the glass cold. 
The warm air passing near the glass has some of its heat absorbed by the 
cold surface. Remembering that cold air cannot hold as much moisture as 
warm air, some of the water vapor in it condenses into tiny droplets of 
water which collect on the glass and, ultimately, drip down the side and 
form a puddle on the table. What has happened is that the air was cooled 
down to its DEW POINT TEMPERATURE, where it changed the moisture content 
of the air from the gaseous state (water vapor) to the liquid state(water).

Now let's spend a few minutes talking about glass. Glass, for the most 
part, is a pretty good electrical INSULATOR. There are exceptions: 
sometimes glass is 'doped' with chemicals to make it a SEMICONDUCTOR. 
Without them, we wouldn't have computers as small as they are now. Glass 
is, compared to some other materials, a good heat CONDUCTOR. Knowing this, 
you should be able to figure out where the water on the underside of the 
table came from. Hint: If you placed a cork coaster underneath the glass 
first, would you still find water underneath the table? Why or why not?
Fun fact about glass: Glass is not a solid as you might think, but rather 
a highly VISCOUS liquid! That's why some of the stained glass windows in 
very old Cathederals in Europe are much thicker at the bottom than they 
are at the top - gravity, over many years, has caused the glass 
to 'flow', !

I suggest you look up the definitions for all the CAPITALIZED words. A 
good place to start is at HTTP://WWW.Weather.com . There is a 
wealth of 
information there, particularly in the "Learn more" section.

You may contact me directly at Karl-Kolbus@email.msn.com if I can be of 
any further help.

Have fun, and keep that mind working!

Karl Kolbus - Not-So-Mad Scientist