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What is Humidity? | Important Fact about Humidity

August 20, 2022
written by Adeel Abbas

The concentration of water in the air is called humidity. Water vapor is invisible to the human eye, but it can be seen in the form of fog or dew.

 What is humidity?

Humidity is the amount of water vapor in the air. Humidity is measured in percentage. A high level of humidity means that the air contains a lot of moisture. Low levels of humidity mean that the air is dry.

Factors Affecting the humidity?

The system of interest has a temperature and pressure that influence Humidity. The relative humidity in cool air is higher than in warm air because of the same amount of water vapor. The dew point is related to the other parameters.

image showing the humidity after rain

As the temperature increases, the amount of water vapor that is needed to achieve saturation increases. When the temperature of a parcel of air decreases, it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can be vastly different.

 Types of humidity

There are three types of humidity

  • Absolute humidity
  • Relative humidity
  • Specific humidity 

Absolute humidity

Absolute humidity is a measure of the actual amount of water in the air, regardless of the air’s temperature. The higher the amount of water vapor, the greater the absolute humidity.

 Relative humidity

A measure of relative humidity is how much water is in a water-air mixture compared to the maximum amount possible. The saturation humidity ratio at a given temperature is compared to the humidity ratio in a particular water-air mixture.

Specific humidity

Specific humidity, the mass of water in a unit mass of moist air, is usually expressed as grams of vapor per kilogram of air or as grains per pound. In meteorology, the specific humidity is a very useful quantity. The rate of evaporation of water from any surface is directly proportional to the specific humidity difference between the surface and the adjacent air.

Effects of humidity

For the purpose of providing for human comfort, health, and safety, and of meeting environmental requirements of machines, and sensitive materials, climate control refers to the control of temperature and relative humidity in buildings, vehicles, and other enclosed spaces.

Important Fact about Humidity

humid air tends to rise due to the fact that water Vapor is a lighter gas than other gaseous components of air at the same temperature. There is a mechanism behind storms and other weather phenomena. It is an indicator of the likelihood of fog, and relative humidity is often mentioned in weather forecasts and reports.

In hot summer weather, it increases the apparent temperature of humans and other animals by preventing perspiration from the skin as the relative humidity increases. The heat index or humidex is used to calculate this effect. A device used to measure humidity is called a hygrometer, and one used to regulate it is called a humidistat or sometimes hygrostat.