What Does A Hygrometer Do?

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What is a hygrometer and what does it do?

Do you know how it feels to be in a dry desert? Now compare that with what you feel when it’s hot and you are in a tropical rainforest. Can you feel the difference? While both can make you feel warm or hot, they are different from each other because of how much humidity is present.

The amount of water vapor in the air can be measured by using a hygrometer. When it is used at home, it can be connected to humidifiers or dehumidifiers to positively affect your health.

The hygrometer

In order to determine how much humidity is in the air, a hygrometer is used. This is a weather device that determines how much water is in the air. Although it plays a great role in weather forecasting, it’s function is not limited there. It also provides useful information to gardeners with greenhouses, people who have saunas, musicians who own fine stringed instruments such as violins and guitars, and as a precaution for home owners who worry about mold.

How does a hygrometer measure humidity?

Plants usually react to the humidity in the air but it may take time for them to do so. There are different types of hygrometers, and the most commonly used are the mechanical hygrometer, psychrometer, and electronic hygrometer.

Mechanical hygrometers

Mechanical hygrometers usually use a piece of twisted fibers that reacts well with humidity. Animal or plant fibers can be used, and it is twisted tightly. When there is low humidity, the fibers tighten the twist. On the other hand, when it is more humid, the twist loosens up.

The piece of fiber can be connected to a spring or needle that identifies whether the air is humid or not. Some mechanical hygrometers such as the “weather house” features a man with an umbrella and woman that comes out of a door depending on the humidity. When it is humid, the man comes out, and when it is dry, the woman comes out.


Developing the psychrometer is one of the first steps in making the measurement of humidity more detailed by giving a specific number. This kind of hygrometer is also known as the wet- and dry-bulb thermometer.

Like the name implies, it makes uses of 2 thermometers. The bulb of one of the thermometers is exposed to the air while the other one is covered with a wet towel. The dry thermometer measures room temperature while the wet one shows a lower temperature because of the wet cloth that causes evaporation and cooling.

The temperature and the humidity both affects the evaporation of the wet cloth and the reading of the second thermometer. The two readings are compared and the difference between the two is known as relative humidity.

Electronic hygrometers

With technology, advancement in hygrometers can also be seen. The electronic hygrometers of today don’t directly measure the humidity, but the resistance or capacitance of instruments exposed to air; they then use that to compute for the humidity.

The capacitance is measured by using of two metal plates. There is an increase in the capacitance of the plates when the air in between the two plates has much water in it.

Similarly, a ceramic material can also be used to determine the humidity through a resistive sensor. When there is much humidity in the air, there is more water vapor that condenses inside the ceramic. The larger amount of water affects the resistance and it is measured to determine the humidity.

Hygrometer apps

In a world where you can do most things with your smartphone, it is not a surprise that there is also an app for determining humidity. The app only works when your phone has a built-in humidity sensor or you can always plug a sensor in through a USB cable.

Some apps don’t necessarily need your phone to be connected to a sensor because it gets the humidity results from a weather station. In order to do this, it first needs to figure out your location. This is why you need your GPS enabled and a connection to the internet for you to use them.

Hygrometers at home

Hygrometers made for home use may have alarms to make sure that the humidity level of your home is just right. They may also be connected to dehumidifiers or humidifiers to make sure that the humidity is kept in the right level.

When your home is too humid, it is very likely for mold and mildew to grow. Mold is related to several health illnesses and it can also cause damage to your property. Too low or too high humidity can also directly affect the health of those living in your home.


Hygrometers are handy tools that can be used to know how much water vapor is in the air, or how humid it is. There are different types of hygrometers, but the most technologically advanced ones are the electronic hygrometers. These can be used in your home to check the humidity for your health’s sake.

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