Dew Point Temperature

Does air hold water vapor?

True or false: hot air can hold more water vapor than cold air.
  1. I don't know.
  2. False, hot air and cold air both hold the same amount of water.
  3. True, hot air holds a lot more moisture. That's why water vapor condenses out of it when it cools.
  4. Trick question: air doesn't "hold" water; the water vapor and air molecules coexist side by side.

    Submit your Answer
The maximum amount of water in vapor form is a strong function of temperature (there can be a lot more when it's hotter) and a weak function of pressure (there can be more when the pressure is higher).

By the way, what color is water vapor?
  1. Clear
  2. White
  3. Gray
  4. Blue

Submit your Answer

A useful way of expressing the amount of water vapor is the dew point temperature, or dew point for short. The dew point is the temperature at which the water vapor in the air would cause saturation.

What's that mean? Remember that the higher the temperature, the greater the amount of water vapor that can be present. So imagine an air parcel (a hunk of air) with some amount of water vapor in it. If you cool the air parcel, eventually there will be more water vapor than can be present in gas form, and some of the water vapor will condense into a liquid. The temperature at which that threshold would be reached is called the dew point temperature.

image image image

Questions or Comments

Technical: E-mail John Fulton < jdfult@nimbus.met.tamu.edu >
Scientific: E-mail Dr. John Nielsen-Gammon. < nielsen@ariel.met.tamu.edu >

Copyright © 1996-2003 Texas A&M University, Texas A&M Atmospheric Sciences Department and Dr. John Nielsen-Gammon. All rights reserved.