||This article does not have any sources. (October 2011)|
Water vapor is water that is in the form of a vapor, or gas. It is a part of the water cycle. When liquid water is heated to boiling point, 100 degrees Celsius (212 F]], it all turns into vapor. Water vapor can also be produced directly from ice; this is called Deposition. Steam is water vapor, but clouds are liquid water. Water vapor affects weather conditions. Water vapor is found in most of the air. In the cold, breathing out causes the water vapor breathed in to freeze.
Water vapor weighs less than air, thus slightly reduces the lift produced by an aircraft wing.
Water vapour is a big cause of the greenhouse effect.