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water vapor

a dispersion, in air, of molecules of water, especially as produced by evaporation at ambient temperatures rather than by boiling.
Compare steam (def 2).
Origin of water vapor
1875-80 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for water vapor
  • The warming of the seas and lakes, moreover, means more water vapor in the air.
  • The brilliant clouds likely formed from the hundreds of tons of water vapor emitted from the shuttle's engine during takeoff.
  • As of yet, there is not even agreement as to whether water vapor plays a positive effect or a negative one.
  • Climatologists are only beginning to model the role that water vapor plays in atmospheric circulation.
  • The silica gel can hold a large amount of water in a small space-it essentially acts as a sponge for the water vapor.
  • New ions become the centers of water vapor condensation.
  • Methane is not really a greenhouse gas since water vapor blocks all the photons that methane blocks.
  • The water vapor would then absorb additional photons.
  • More particles means more cloud droplets, but they're competing for a limited pool of water vapor.
  • They form high in the atmosphere when the mixture of water vapor in aircraft exhaust and air condenses and freezes.
water vapor in Science
water vapor  
Water in its gaseous state, especially in the atmosphere and at a temperature below the boiling point. Water vapor in the atmosphere serves as the raw material for cloud and rain formation. It also helps regulate the Earth's temperature by reflecting and scattering radiation from the Sun and by absorbing the Earth's infrared radiation. See also vapor.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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