Condensation forms when warm, moist air touches a surface that is colder than the dew point of the warm air. As that air becomes colder and its temperature drops below its dew point, it must release excess moisture to reach its new, lower dew point. It releases moisture in the form of water, which appears on the colder surface.
A common example of moisture condensation is when a glass of ice water “sweats” when you bring it outside in the summer. When the warm, moist air touches the cold glass, the temperature of the air drops below its dew point, forcing the air to release moisture in the form of water on the sides of the glass. There are many things in our homes that put moisture into the air. Normal breathing and perspiration add 3 pints of water to the air every day for each person in your home. In fact, every activity that uses water adds more moisture to the air including cooking, taking showers, dishwashing, and doing laundry.