[L. humiditas]
Moisture in the atmosphere.
The moisture content of air usually is expressed as relative humidity. This indicates the amount of water vapor in the air compared with the maximum amount of moisture the air could contain at that temperature and atmospheric pressure. Air that is fully saturated with moisture has 100% relative humidity. When air that is fully saturated is cooled, the excess moisture condenses, as in the case of dew or moisture on a cold glass in the summer.

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