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Humidity: Effect - Hygrometer

Humidity: effect - measurement - Hygrometer  What is humidity?


What is humidity?

Humidity (relative humidity) can be expressed as the amount of water vapor present in the air expressed as a percentage of the maximum air load of water vapor at that Celsius temperature at which the humidity was measured. For example, air can carry an estimated 2.2 grams of water vapor per A cubic meter at a temperature of ten below zero. If we find at that temperature an estimated 1.1 grams of water vapor per cubic meter, we can say that the humidity in the air is equivalent to fifty percent.[1]



How to measure humidity in the air

The humidity rate in the air can be measured using a device called a psychrometer or hygrometer, which uses two temperature sensors, one of which measures the dry temperature and the other measures the wet temperature, where the wet temperature sensor contains a quantity of water in its base to evaporate and absorb heat. Which would reduce the temperature, and in order to be able to measure the relative humidity, it is necessary to take the readings of the two sensors (dry and wet) and find the difference between them, and the device (the cyclometer) should be hung in the open air until its reading is proven and recorded.[2]



Humidity effect

The effect of humidity reaches all living organisms on the face of the globe to the extent of affecting the growth of plants and animals alike. As for man, he depends on getting rid of excess heat on the natural process of sweating, but during exposure to high humidity environments, the rate of evaporation of sweat decreases as it depends The rate of blood pressure depends on how much the body gets rid of the excess heat inside it through sweating, causing a state of high body temperature (hyperthermia). All of what was mentioned, the effect of humidity reaches even electronic devices and industrial equipment in general. [3]



Humidity measurement methods

1. Psychrometer

It is a device that consists of two thermometers, one of which is dry and the other is wet. Humidity is measured by comparing the two temperatures indicated by the two scales. This device is considered one of the simplest methods used to measure humidity.

Suspended Psychrometer: Also known as rotary, which consists of two thermometers, one dry and the other wet, are installed inside a metal frame with a rotating hand to move it manually, in a circular and quick way to obtain the necessary ventilation, and this is done by holding the hand on the device, raising it above the head and then Rotate it several times, and the humidity is determined by measuring two successive ventilation readings, after which the humidity is determined according to the psycrometer tables.


Psychrometer: It is similar to a suspended psycrometer, as it contains dry and wet calibers, except that the ventilation process does not occur through a manually operated fan, but is driven by an electric motor, so an air current is generated to measure the humidity.



2. Capillary hygrometer

It is also called a hygrometer. This device consists of a group of hair tufts that may be human or horse; Because the hair expands when humidity increases and contracts when it decreases, and a feather is installed at the end of these tufts, which moves in front of a ruler with numbers from zero to one hundred.



3. Relative humidity meter

It is also called a hygrograph, where the principle of the relative hygrometer is based on a similar principle to the capillary hygrometer. From the levers that transfer it to the tip of the feather, which in turn draws the ratio on a twisted diagram on a cylinder that moves in a fixed rate, and the hygrometer is placed in the inside of the monitoring cage.



4. Thermometer and relative humidity

It is a device that measures and records the temperature and relative humidity on the cylinder itself, and relies on a heat-sensitive metal ring. As for the measurement of temperature, it uses a strand of hair.




Humidity can be measured through a device known as a hygrometer, and this device has many different types, and here are some of these types:[4]


1. Mechanical hygrometer

Humidity is measured through a mechanical hygrometer through the use of some micro-organic materials, such as human hair, where a hair from the human head is fixed on a pointer in the measuring device, and this hair expands or contracts according to the amount of moisture it is exposed to, which leads to a change in the indicator , to measure the degree of humidity.


2. Electronic hygrometer

Humidity can be accurately measured through the use of an electronic hygrometer, which is based on the principle of changing electrical resistance; Where two types of metal plates are exposed to moist air, and the higher the humidity, the greater the ability of those plates to store electrical charges, then the amount of charges that were stored in the plates is calculated.[5]


3. Cyclometer

The Psychrometer consists of two thermometers, one dry and the other covered with a piece of wet cloth, and the temperature of the wet scale is lower than the temperature of the dry one, due to the coldness produced by the evaporation of water, then the difference between the two temperatures is calculated in the scale to extract the moisture content [6]



The importance of measuring humidity

Humidity is defined as the amount of water vapor present in the air,[7] and the measurement of humidity is extremely important in our daily lives, apart from its connection to weather forecasts, and this importance is as follows:[8]

1.      Human and animal health: Increasing humidity in the air negatively affects human health, and can result in cases of heat stress or breathing problems, and the danger of humidity is not limited to humans, as it also affects animals such as problems in reproduction and increased mortality rates.

2.     Precipitation: The amount of water vapor in the air affects the amount of precipitation.





1.      "Humidity",, Retrieved 8-12-2018. Edited.

2.     "Instruments",, Retrieved 26-11-2018. Edited.

3.     Benjamin Elisha Sawe (25-4-2017), "What Is Humidity And How Does It Affect Life On Earth?"،, Retrieved 26-11-2018. Edited.

4.     "Hygrometer",, Retrieved 22-1-2019. Edited.

5.     Chris Woodford. (14-7-2018), "Hygrometers"،, Retrieved 22-1-2019. Edited.

6.     "Psychrometer",, Retrieved 22-1-2019. Edited.

7.      "What Is Humidity And How Does It Affect Life On Earth?",, Retrieved 23-1-2019. Edited.

8.     "Why is humidity important?",, Retrieved 06/06/2022. Edited.