What is the term for the amount of water vapor in the air compared to the maximum amount it can hold?

The term that describes the amount of water vapor present in the air relative to the maximum amount it can hold is known as relative humidity. Relative humidity is expressed as a percentage and indicates how saturated the air is with moisture. For example, if the air can hold a maximum of 20 grams of water vapor but currently contains 10 grams, the relative humidity would be 50%.

This concept is essential in understanding weather patterns, comfort levels, and various atmospheric processes, as it relates to how close the air is to saturation. When relative humidity reaches 100%, the air is fully saturated with moisture, which can lead to the formation of clouds and precipitation.