higromeeter

A higromeeter, more commonly spelled hygrometer, is an instrument used to measure the amount of water vapor present in the air, i.e., humidity. The term hygrometer derives from Greek hygros meaning moisture and metron meaning measure. While hygrometer is the standard modern spelling, higromeeter appears as a variant in some sources or translations.

Hygrometers operate on several principles. Hair-based devices use the natural length change of human or animal hair with humidity. Electrical hygrometers rely on changes in capacitance or resistance of a hygroscopic material as its moisture content varies. Dew-point or chilled-mirror hygrometers determine humidity by cooling a surface until condensation forms on the mirror. Psychrometers use paired dry and wet bulb thermometers to compute relative humidity from temperature readings. Some hygrometers are integrated into electronic sensors that provide digital readouts.

Common applications include weather observation and forecasting, HVAC system control, food and pharmaceutical storage, museums and archives preservation, electronics manufacturing, and consumer weather stations or smart devices. Hygrometers may report relative humidity, absolute humidity, or dew point, depending on construction and intended use.

Calibration and accuracy are important considerations. Relative humidity readings can be influenced by temperature, airflow, and contamination. Calibration often involves exposure to known humidity environments produced by saturated salt solutions or reference instruments. Modern digital hygrometers typically combine sensors with calibration routines to maintain acceptable precision for their intended purpose.