Learn more physics!
Are there water vapour in the air?
- Lim Feng Yi (age 11)
Tampines North Primary School, SIngapore
Yes! There can actually be a whole lot of water vapor in the air we
breathe. The word for how much water vapor there is in the air is
"humidity". And the warmer it is, the more humidity the air can hold.
At room temperature, one cubic meter of air can hold as much as 20
grams of evaporated water! But you don't have to believe me. Here's
something you can try to prove it to yourself...
Take a cold can of soda or a glass of cold ice water and set it out
in the air. The air around the glass is colder than the rest of the
air, so it can hold less water vapor. And when the air can't hold as
much water vapor as it actually has, some of the water will condense
into a liquid form. This is why you should see liquid water condensed
on the outside of the glass or can.
(republished on 08/01/06)
Follow-Up #1: Is water a gas?
is water gas
- milen (age 8)
Nice question. Water can be a gas and it can be a liquid and it can be a solid. When itís cold, it forms a solid, with the water mlecules arranged in a regular pattern that canít bend or flow easily. When itís hot and the pressure is low the molecules fly apart, forming a gas. In between, the molecules stick together, but in a loose, irregular, tumbling sort of way- thatís a liquid.
Ordinarily at room temperature in the atmosphere, some water can be liquid so long as thereís enough water in the gas too. When thereís just enough water in the gas, the molecules jumping out of the liquid into the air are just balanced by ones coming from the gas into the liquid.
(published on 11/14/06)
Follow-up on this answer.