The global hydrological cycle Water can exist in all three states at temperatures found on earth. Dew point temperature to which air must be cooled for it to be saturated. Can be expressed in a number of different ways. Absolute humidity grams per cubic meter , similar to density, changes if volume changes. Specific humidity grams per kilogram of air , does not change if volume changes.
Clouds are water droplets that have condensed from atmospheric water vapor.
Some clouds are made of ice crystals. Often, clouds form because air rises. As the air rises, the water vapor condenses. Adiabatic processes adiabatic means no exchange of energy. An air parcel that is less dense than surrounding air is buoyant, and will therefore float.