The hygrometer is used for measuring

The hygrometer is used for measuring relative humidity. Relative humidity is a measure of how much water vapor is in the air, compared to the maximum amount of water vapor that the air could hold at a given temperature. The hygrometer works by measuring the amount of water vapor in the air, typically using a hair or synthetic sensor that changes in length or electrical resistance as the humidity changes. This change is then translated into a reading that can be displayed on a gauge or digital display. By measuring relative humidity, the hygrometer is useful in a variety of applications, such as weather forecasting, monitoring of indoor air quality, and control of industrial processes.