Condensation happens one of two ways: Either the air is cooled to its dew point or it becomes so saturated with water vapor that it cannot hold any more water. Dew point is the temperature at which condensation happens. ... When warm air hits the cold surface, it reaches its dew point and condenses.

What is the main cause of condensation?

Condensation occurs when warm air collides with cold surfaces, or when there's too much humidity in your home. When this moisture-packed warm air comes into contact with a chilly surface, it cools down quickly and releases the water, which turns into liquid droplets on the cold surface.

Why does water condense on glass?

When water vapor in the air comes into contact with something cool, such as the outside of a cold glass of lemonade, its molecules slow down and get closer together. When that happens, the gaseous water vapor turns back into liquid water droplets. That's condensation!