How does water evaporate?

[gustavo]

I was just wondering and apologize if you consider this OT,
Why and how water evaporates from the soil? I mean no way it gets any close to 100 Celsius so it should be in a solid state in the atmosphere. Does it get in a solid state to the clouds? Or is there any energy I am missing involved.

Thank you in advance,
Gustavo.-

 

[klaviernista]

Check out this link for more info. Its pretty good, but may not have the detail you want.

http://www.enviroliteracy.org/article.php/704.php

 

[klaviernista]

also, check this link out for a more colorful explanation. Oh culligan man!

http://www.culliganlaredo.com/culligan_water_fundamentals.htm

 

[klaviernista]

Also, don't confuse boiling point with vapor pressure. It isn;t necessary for water to be at its boiling point in order for it to evaporate. However, the vapor pressure of water is proportional to its temperature. Think of it like this.

You have a beaker half filled with water and covered with a water impermeable membrane. At room temperature, the space between the liquid water and the membrane contain water vapor. The exact amount can be determined by this experiment: http://www.spsu.edu/chem/1212lab/Exp03.pdf (illustrating daltons law of partial pressures and other boring topics)

At higher temperatures, more water vapor will enter the air between the liquid water and the membrane.
Just like liquid solutions, air can form supersaturated solutions at high temperature.

If you drop the temperature of the solution, eventually the water vapor that is in the air will precipitate out of solution (condensation).

So how does this apply to the real world? Well, the world is one gigantic beaker, with space being the impermeable mebrane (per se) and the land/ocean being the liquid water. Water evaporates from the earths surface at the greatest rate near the equater (where it is hottest). That water vapor is carried around in the atmosphere in the form of clouds until it reaches a point where the air temperature drops below the saturation temperature (commonly known as the dew point). At that point the water precipitates from solution (condenses) and you get rain.

 

[gustavo]

Thank you all !!!
Klaviernista let it clear as water
Gustavo.-

 

[dkozloski]

Don't ignore the process of sublimation where the material in question goes directly from a solid to a gas. Iodine is the usual material used for a lab demo but if you hang your damp laundry on an outside clothes line at -40F. when you bring it back inside in the morning it will be dry. Paved roads will go from ice covered to bone dry over a period of time at -25F and below. (Some observations by an old Alaskan.)