Kosteusasteen

Kosteusasteen is the Finnish term used to describe the level or degree of moisture in air or in materials. In meteorology and building science it is most commonly expressed as relative humidity, the percentage of water vapor present in the air relative to the maximum amount the air can hold at a given temperature. Related measures include absolute humidity and specific humidity, which quantify moisture content without reference to temperature.

Kosteusasteen is typically measured with hygrometers or psychrometers. Digital hygrometers provide direct readings, while psychrometers use dry-bulb and wet-bulb temperatures to derive humidity. In materials testing, moisture content can be assessed by gravimetric methods or with moisture meters. The concept is used across fields such as weather forecasting, indoor climate control, construction, and storage.

The level of moisture influences condensation, mold risk, and material properties. Excessive kosteusaste can lead to mold growth, damage to finishes, and structural problems, while very low moisture can cause skin irritation and static electricity. For comfort and health, many guidelines recommend maintaining indoor relative humidity roughly within 40–60 percent, though optimal ranges may vary by season and climate. In Finnish usage, the term appears in building codes, weather reports, and environmental monitoring, where kosteusaste data support assessments of comfort, energy efficiency, and moisture-related risks.