* Water vapor in the air: Air always contains some amount of water vapor, which is invisible water molecules suspended in the air.
* Cold surface: When you place a cold glass in warm air, the glass's surface becomes colder than the surrounding air.
* Temperature difference: This temperature difference creates a boundary where the warm, humid air meets the cold glass surface.
* Saturation point: As the warm air comes into contact with the cold glass, it cools down. Cooler air can hold less water vapor. When the air cools enough, it reaches its dew point, the temperature at which the air becomes saturated with water vapor.
* Condensation: At the dew point, the water vapor in the air can no longer be held as a gas and begins to condense into liquid water droplets, forming the visible condensation on the cold surface.
Think of it this way: Imagine a sponge that can hold a certain amount of water. If you squeeze the sponge, water spills out. Similarly, when you cool the air down, it can't hold as much water vapor, so it "spills out" as condensation.
