The concentration of water vapour present in the air is known as humidity. The widely employed primary measurements of humidity are absolute, relative, and specific humidity. In this article, let us learn more about the three primary humidity measurements.

Table of Contents

Types of Humidity

Absolute Humidity

Absolute humidity describes the water content present in the air and is expressed in either gram per cubic meter or grams per kilogram. The absolute humidity in the atmosphere ranges from near zero to roughly 30 grams per cubic metre.

Mathematically, absolute humidity is defined as the mass of the water vapour divided by the volume of the air and water mixture, which is expressed as

\(\begin{array}{l}\Delta H=\frac{m_{H_{2}O}}{V_{net}}\end{array} \)

Where mH2o = Mass of the water vapour
Vnet = Volume of air and water mixture

The absolute humidity varies with respect to air temperature, and pressure changes if the volume is not fixed. The mass of water vapour per unit volume in the equation is also defined as volumetric humidity.

Relative Humidity

The relative humidity of an air-water mixture is defined as the ratio of the partial pressure of water vapour in the mixture to the equilibrium water vapour pressure over a flat surface of pure water at a given temperature. It is normally expressed as a percentage. A higher percentage indicates that the air-water mixture is more humid.

Relative humidity is a crucial metric that is used in weather forecasts as it is an indicator of the likelihood of precipitation, dew or fog. In hot summer weather, a rise in relative humidity increases the temperature of humans by hindering the evaporation of perspiration from the skin.

Specific Humidity

The ratio of water vapour’s mass to the air parcel’s total mass is known as specific humidity.

Effects of Humidity

Animals and Plant Life

Humidity determines which animals and plants can thrive in a given environment. When the air has a high moisture content, the sweat cannot evaporate. As a result, our bodies feel hot and sticky. In such cases, the body temperature is regulated by excessive sweating, increased blood circulation and respiration.


Electronic devices are designed to operate under specific humidity. During high humid conditions, the moisture may increase the conduction of permeable insulators leading to malfunction. Low humidity makes materials brittle. Condensation is a substantial danger to electronic items, regardless of the stated humidity range. When an electronic item is moved from a cold place, say a garage to a humid such as the house, condensation coats circuit boards and other insulators, short-circuiting the equipment. Low humidity favours the build-up of static electricity which results in the shutdown of computers when the discharge occurs.


High humidity has a negative effect on the capacity of chemical plants that use furnaces as part of certain processes.

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Frequently Asked Questions – FAQs


What is humidity?

The concentration of water vapour present in the air is known as humidity.

What are the main types of humidity?

Absolute humidity, relative humidity, and specific humidity.

What is absolute humidity?

Absolute humidity is a quantity that describes the water content in the air regardless of the temperature.

What is specific humidity?

The ratio of the mass of water vapour to the total mass of the air parcel is called specific humidity.

Explain the importance of humidity in the production and maintenance of electronic devices.

Electronic devices are made to work under specific humidity. During extreme humid conditions, the water vapour content may rise the conduction of permeable non-conductors (insulators), making them malfunction. Low humidity makes objects brittle. One fatal danger to electronic components, regardless of the humidity range, is condensation. Low humidity drives the accumulation of static electricity, which results in the malfunctioning of computers when the discharge occurs.
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