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
- Effects of Humidity
- Frequently Asked Questions – FAQs
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.
Electronics
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.
Industry
High humidity has a negative effect on the capacity of chemical plants that use furnaces as part of certain processes.
Check out the following related links for your better understanding:
Watch the video and understand the factors affecting evaporation.
Frequently Asked Questions – FAQs
Q1
What is humidity?
The concentration of water vapour present in the air is known as humidity.
Q2
What are the main types of humidity?
Absolute humidity, relative humidity, and specific humidity.
Q3
What is absolute humidity?
Absolute humidity is a quantity that describes the water content in the air regardless of the temperature.
Q4
What is specific humidity?
The ratio of the mass of water vapour to the total mass of the air parcel is called specific humidity.
Q5
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.
FAQs
Relative humidity, often expressed as a percentage, indicates a present state of absolute humidity relative to a maximum humidity given the same temperature. Specific humidity is the ratio of water vapor mass to total moist air parcel mass. Humidity plays an important role for surface life.
What is the relation between relative humidity and specific humidity? ›
Specific humidity is a simple percentage measurement of the total water in the atmosphere, the other term for this is the absolute humidity. Relative humidity on the other hand is the amount of water in the atmosphere as a percentage of the maximum carrying capacity of the air.
Which is more important relative humidity or absolute humidity? ›
Relative humidity, rather than absolute humidity, is a dominant factor in the case of drying secretions in the upper airway when using such a humidifier.
What does 100% relative humidity look like? ›
It just means that the air is holding as much moisture as it can at a given temperature, in the form of water vapor, which is an invisible gas. However, near 100% relative humidity, you can get water vapor condensing into very small water droplets to form clouds, including fog near the surface.
What humidity level is uncomfortable? ›
less than or equal to 55: dry and comfortable. between 55 and 65: becoming "sticky" with muggy evenings. greater than or equal to 65: lots of moisture in the air, becoming oppressive.
What is the difference between absolute humidity and specific humidity? ›
Specific humidity is a measurement method, which is similar to the absolute method. The only difference is that instead of considering air volume, this calculation considers the total air mass.
What is the difference between absolute specific and relative humidity? ›
“Absolute humidity” is how much water vapour is present in the air as a simple measure of quantity, i.e. so many grams of water per cubit meter. “Relative humidity” is a measure of how much water vapour is in the air compared to how much the air could absorb, and so is expressed as a percentage.
What is the best humidity level for humans? ›
Ideal humidity levels
It's ideal to keep the humidity in your home between 30% and 50%. Humidity that's too low or too high can cause problems. Low humidity can cause dry skin. It also can bother the inside of the nose and the throat.
Why don't we use absolute humidity? ›
Absolute humidity does not indicate the humidity level of the air because at a lower temperature the more water vapor in the air is saturated. Therefore, to describe the humidity of air, relative humidity is used.
Why is absolute humidity rarely used? ›
Absolute humidity is the weight of water vapor per unit volume of air, usually measured in units of grams of water vapor per cubic meter of air. Absolute humidity is not often used to express the moisture content of air because it is sensitive to changes in both the temperature of the air and atmospheric pressure.
A warm air mass can be mixed with more water vapor than a cool air mass of the same size. Absolute Humidity is independent of temperature while relative humidity is a function of temperature.
At what humidity does mold grow? ›
Relative humidity greater than 60 percent is likely to result in condensation in the building, which can lead to mold growth.
What is the most humid place on earth? ›
According to this analysis, seven countries have cities with 365 humid days per year. So it's not surprising that those countries dominate the global list: Libreville, Gabon; Balikpapan, Indonesia; Macapa, Brazil; Singapore; Colombo, Sri Lanka; Port Moresby, Papua New Guinea; and Cartegenia; Colombia.
What time of the day is relative humidity generally the highest? ›
In general, assuming the dewpoint or absolute humidity does not change, the relative humidity will be highest in the early morning when the air temperature is coolest, and lowest in the afternoon when the air temperature is highest.
What are the three types of humidity? ›
What are the main types of humidity? Absolute humidity, relative humidity, and specific humidity.
What is the difference between absolute humidity and actual humidity? ›
Or to put it simply, relative humidity indicates the actual water content of air as a percentage of the maximum amount it could possibly hold. The term absolute humidity is less common: it describes the actual amount of water vapour in the air in g/m3. This also depends on the temperature of the air.
How do you calculate absolute humidity? ›
The formula to calculate absolute humidity (AH) is: AH = (mv / Va) where: - mv is the mass of the water vapor (in grams) - Va is the volume of the air (in cubic meters) To use this formula, you need to know the mass of the water vapor and the volume of the air.
