What defines the dew point?

The dew point is defined as the temperature at which air becomes saturated with water vapor. When air cools to its dew point, it cannot hold all of its moisture in vapor form, leading to condensation. This means that water vapor in the air begins to condense into liquid water, resulting in dew, fog, or clouds. Understanding the dew point is critical in various fields, including meteorology and building science, as it affects humidity levels and condensation risks.

Dew point is distinct from other concepts such as the temperature at which water vapor evaporates or the temperature at which air reaches a specific relative humidity. While those factors are important in the context of humidity and temperature, they do not accurately represent the phenomenon of saturation, which is the core characteristic of the dew point.