Moisture

Moisture refers to the presence of water within or between substances. It can describe water in the air as humidity or water contained within solids, liquids, or porous materials. Moisture plays a central role in weather, agriculture, food science, construction, and materials engineering.

Atmospheric moisture is commonly described by relative humidity, absolute humidity, specific humidity, and dew point. Relative humidity expresses the current amount of water vapor as a percentage of the maximum possible at a given temperature. The dew point is the temperature at which air becomes saturated and condensation begins. Instruments such as hygrometers, psychrometers, and dew-point meters are used to measure moisture in the air.

In materials science and engineering, moisture content denotes the amount of water present in a material, often expressed as a percentage of total or dry weight. In foods, water activity and moisture content influence texture, safety, and shelf life. In soils and plants, soil moisture affects hydration, nutrient transport, and growth. Drying, conditioning, and moisture control are common processing steps across many industries to achieve desired properties and prevent deterioration.

Moisture can exist as free water, bound water, or water vapor. Its management and measurement are essential for predicting weather, optimizing agricultural practices, preserving cultural artifacts and building materials, and ensuring product quality and performance.