QS Study

“The relative humidity of air is 60%”—this statement means.

Relative humidity is defined as the ratio of the mass of water vapour present in a given volume of air at a particular temperature to the mass of water vapour required to saturate the same volume of air at the same temperature. It is the amount of water vapor (vapor pressure) that is in the air. It is a percentage of how much moisture the air could possibly hold.

(i) the vapour pressure at room temperature is 60/100 or 3/5 part of the saturated vapour pressure at the same temperature;

(ii) the water vapour present in a certain volume of air in the room is only 60% of the water vapour needed to saturate the air at the room temperature.

Experiment- Spray some water inside a room and you will see that water vapour increases. But you will see that temperature remains constant. Again, relative humidity and dew point will be increased. What is the meant?

When water is sprayed inside a room water vapour in air increases. But since temperature remains same, hence the mass of water vapour needed to saturate the air inside the room at that temperature remains unchanged. In the definition of specific heat numerator increases and denominator decreases. Hence relative humidity increases. Obviously, dew point also increases.

Relative humidity is a mixture utility of the real humidity substance of the air, the temperature, and the barometric pressure. Saturation occurs when the air is holding the utmost amount of water vapor probable at the existing pressure and temperature. Saturation is equal to 100% relative humidity, resulting in precipitation. Influence of relative humidity in our daily life is important which affect our physical and mental state. So we need to know the significance of relative humidity.