Niiskust

Niiskust is a term used in Estonian to describe moisture, i.e., the amount of water present in a substance or the amount of water vapor in the air. In English, related concepts are moisture content and relative humidity. The term appears in several fields, including construction, agriculture, meteorology, and materials science.

Moisture content refers to the water contained in a solid material. It is commonly expressed as a percentage of the material's mass, with wet basis (water mass divided by total mass × 100%) and dry basis (water mass divided by dry mass × 100%). Oven-drying is a common method to determine moisture content, though alternative methods use infrared or dielectric sensors.

Relative humidity describes the amount of water vapor in the air relative to its maximum at a given temperature. It is expressed as a percentage. Other related measures include dew point, the temperature at which air becomes saturated, and absolute humidity, the mass of water vapor per volume of air.

Why it matters: Excess moisture can promote mold growth, wood rot, corrosion, and deterioration of building materials; too little moisture can damage plants and reduce product quality. In agriculture and horticulture, soil moisture level affects plant health and irrigation planning. In industrial contexts, controlling moisture is essential for product stability and process efficiency.

Measurement tools include hygrometers, psychrometers, moisture meters, and sensors that estimate moisture content in solids or soils. Understanding niiskust helps manage indoor air quality, crop production, and material performance.