When air is cooled, what eventually occurs to its relative humidity?

When air is cooled, its relative humidity eventually reaches 100% or saturation. This occurs because cooler air holds less moisture than warmer air. As the temperature decreases, the capacity of the air to hold water vapor diminishes, leading to an increase in relative humidity.

Relative humidity is a measure of the current amount of moisture in the air compared to the maximum amount of moisture the air can hold at that temperature. Therefore, when the temperature drops, the amount of moisture already present in the air becomes a larger percentage of the total capacity, ultimately leading the relative humidity to increase. Once the air temperature is reduced sufficiently, it will reach a point of saturation (100% relative humidity), and any further cooling can result in condensation, where water vapor begins to condense into liquid water. This principle is vital in applications related to water damage restoration, as it affects drying processes and the potential for mold growth.