25-04-2012, 01:01 PM
Water In the Air
water_in_the_air.ppt (Size: 1.04 MB / Downloads: 44)
Water
Only substance commonly found in three different forms in the atmosphere
Liquid
Gas
Solid
Water also has the ability to “disappear” as part of the water cycle
Evaporation
Evaporation-the process by which a liquid changes to a gas
When water molecules near a surface gain enough energy they escape (form a gas)
The more water is heated the faster the molecules move and the faster evaporation takes place
Sublimation
One example of sublimation occurs in the Rocky Mountains
Chinook winds blow in from the Pacific-they become very warm and dry
Can go from -5 to 60 or 70 and snow changes directly to water vapor
Condensation
Some of the water vapor is forced to appear as a liquid
This is called condensation-process by which a gas is changed to a liquid
Warm air can hold more water vapor than cold air because there is more space between the molecules
Clouds and Precipitation
Form a cloud-large collection of very tiny droplets of water or ice crystals
Fog-when clouds form at or near the earth’s surface
Conditions in the atmosphere determine the type of cloud that forms