The liquid that condenses from water vapor on a surface is called dew.

Here's how it happens:

1. Water vapor in the air: The air around us always contains some amount of water vapor, which is invisible to the naked eye.

2. Cooling surface: When a surface cools down, it becomes colder than the surrounding air.

3. Condensation: The water vapor in the air comes into contact with the cool surface, and its temperature drops. As the vapor cools, it loses energy and changes its state from a gas (water vapor) to a liquid (water droplets). This is condensation.

4. Dew formation: These water droplets then form on the surface, creating dew.

Dew formation is a common phenomenon, especially on cool mornings or evenings when the ground and objects cool down quickly.