At temperatures below the dew point, the rate of condensation will be greater than that of evaporation, forming more liquid water. In technical terms, the dew point is the temperature at which the water vapor in a sample of air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. In normal conditions, the dew point temperature will not be greater than the air temperature, since relative humidity typically does not exceed 100%. If all the other factors influencing humidity remain constant, at ground level the relative humidity rises as the temperature falls this is because less vapor is needed to saturate the air. In liquids, the analog to the dew point is the cloud point. When the temperature is below the freezing point of water, the dew point is called the frost point, as frost is formed via deposition rather than condensation. The more moisture the air contains, the higher its dew point. The dew point is affected by the air's humidity. When this occurs through the air's contact with a colder surface, dew will form on that surface. When the air is cooled below the dew point, its moisture capacity is reduced and airborne water vapor will condense to form liquid water known as dew.

This temperature depends on the pressure and water content of the air. The dew point of a given body of air is the temperature to which it must be cooled to become saturated with water vapor.

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