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A hygrometer [haɪˈɡrɒmɪtə] is an instrument used for measuring the moisture content in the atmosphere

Types of Hygrometers and Their Uses

digital hygrometer and thermometerHygrometers measure humidity in the air, track changes in electrical conductivity and define precise changes in moisture that affect industrial production and products used in military, medical and surface-coating applications. The most common uses for hygrometers include forecasting weather and maintaining a comfortable humidity in homes, commercial establishments and museums.

Bad Hair Days

Bad hair days are caused by hair expanding and contracting due to humidity. Human hair expands in atmospheres with high humidity and contracts when conditions are drier. Some types of hygrometers use human hair to measure relative humidity. Using hygrometers, people can adjust the humidity in their homes with humidifiers and dehumidifiers to make rooms feel more comfortable without using excessive energy to produce higher or lower temperatures. When air is moist, body perspiration doesn’t evaporate as quickly, which makes you feel hotter than the temperature warrants. When air is dry, skin moisture evaporates quickly and makes you feel cooler.

Hygrometers use various technologies to measure relative humidity, which is the amount of moisture that air can hold at a certain temperature and pressure. The closer to 100 percent the meter comes, the more moisture is in the air. The lower the figure, the drier the air is. Overly dry or moist conditions generate many unwanted effects such as causing paint to peel, stimulating mold growth, making people feel hotter and colder and warping delicate equipment and fine musical instruments. High moisture levels can cause foods to spoil faster and aggravate allergies.

Hygrometer Overview

Many instruments measure water in solid, liquid or gaseous form, but hygrometers concentrate on water vapor in the air, which is often the most difficult water-related content to measure. Measuring and calibrating humidity and correcting moisture levels automatically are the main goals of using hygrometers. Different technologies measure humidity by using the dew point of water, the tensile properties of human hair and other fibers, condensation of moisture on a mirrored surface and the differences between evaporation rates on wet and dry surfaces.

The more complex types of meters measure more accurately depending on how sensitive you need measurements to be. For example, in surgery or ICU units, accuracy could have life-and-death consequences, so hygrometers need to measure humidity with great precision. In your office, a general reading will suffice to determine relative humidity and comfort. Inexpensive devices might vary up to 10 percent, but these variations would have few consequences in home-humidity situations unless a person were extremely sensitive to humidity changes.

Hygrometers run the gamut from simple meters to use in the home to detailed instruments capable of measuring the slightest humidity changes in high-tech industrial processes and military and scientific applications. Instruments range from handheld instruments to sensitive, self-contained units that monitor clean rooms, computer server rooms and air streams. Today, you can even get cellphone apps that act as hygrometers, but these apps merely contact local weather stations to download information instead of measuring humidity directly.