Key concepts
Warm air can contain more water vapor than cool air. The dew point is the temperature at which the nearby air becomes saturated. A surface below that temperature removes energy from colliding vapor molecules. Some remain together as liquid, first forming tiny nuclei and then larger droplets.
The droplets in this model are visually enlarged. Dew point is calculated with the Magnus approximation; collection rate is an educational estimate, not a laboratory calibration.
Explore further
Questions: Why does a cold drink “sweat”? Why do windows fog first at their coldest edges? Can a warm surface collect dew?
Applications: cloud formation, dehumidifiers, distillation, greenhouse control, fog harvesting, and heat exchangers.
Misconception: water on the outside of a glass does not leak through it. It comes from water vapor already in the surrounding air.