Hygrometers
Hygrometers are used to measure the amount of water vapor or humidity in the atmosphere, soil, or other spaces. Instruments that measure humidity typically also measure temperature, pressure, mass, or even a mechanical or electrical change in a substance that absorbs moisture because those factors can also affect humidity.
The first recorded invention of a hygrometer was by Leonardo da Vinci in 1480. Electronic devices use the condensation temperature (also called the dew point), the point of full vapor saturation. Other devices detect and measure changes in a material’s capacitance or resistance to determine humidity. Resistive humidity meters measure the changes in the ability of a substance to hold a static charge. Capacitor-based hygrometers measure the change in the ability of the material to transmit electricity. Most of these instruments are designed to report results as relative humidity (RH). Relative humidity is a calculation of the percentage of water saturation relative to the maximum saturation at a specific temperature.
Hygrometers are used in greenhouses, incubators, saunas, humidors, and museums. They can be used to help protect items like wooden musical instruments that can be damaged by too much or too little humidity.
Hygrometers are useful in the coating industry because paints and other coatings can be sensitive to humidity and dew point, which affect their successful application.