fuktighet

Fuktighet, or humidity, refers to the amount of water vapor in air or the moisture content of a substance. In meteorology and everyday use, it describes how much water vapor the atmosphere contains and how this affects weather, comfort, and various processes.

Relative humidity is the most common way to express outdoor and indoor moisture. It is the ratio of the current water vapor pressure to the maximum vapor pressure the air can hold at a given temperature, expressed as a percentage. Absolute humidity measures the mass of water vapor in a unit volume of air, typically grams per cubic meter. Specific humidity expresses the ratio of the vapor mass to the total mass of moist air. The dew point is the temperature at which air becomes saturated and condensation begins.

Measurement methods include hygrometers and psychrometers, the latter using dry-bulb and wet-bulb temperatures to calculate relative humidity. Modern sensors provide continuous RH readings for climate control, weather forecasts, and environmental monitoring.

In buildings, humidity influences comfort, indoor air quality, energy use, and material performance. Too much moisture can promote mold growth and condensation; too little can cause skin and mucous membrane irritation and static electricity. In agriculture and storage, appropriate humidity levels affect crop health and product quality. Humidity also interacts with temperature to shape weather patterns, with dew, frost, and fog arising when air cools to its dew point.