Water vapor will begin to buildup in the air in the covered
glass. Some of that water vapor will begin to condense. The
amount of water vapor will increase until the rates of condensation and
evaporation become equal. The water vapor concentration won't
change after that. The air is saturated with water vapor.
When air is saturated it is filled to capacity with water
vapor. The actual amount of water vapor will depend on the air's
temperature, warm air can contain more water vapor than cold air can.
