The sun provides the energy needed to evaporate water. Global winds then carry the water vapor through the troposphere. When the air cools, water vapor condenses into tiny water droplets, which form clouds. Eventually, the water in clouds may fall to the earth's surface as rain or snow. In time, some of this water flows into rivers, lakes, oceans, or the ground.
Evaporation continues the cycle.
In order for clouds to form in the atmosphere, moist air must be cooled below its dew point. Water vapor condenses in the air after the air has become saturated. The water vapor in the warm air you exhale condenses as it meets the cold outside air. We are now going to do an activity that will demonstrate condensation. Fill a beaker one-third full with water.