RAGHAV JAIN, Chandigarh
Water vapour is a major part of our atmospheric circulation and precipitation mechanism. Water as we know it can exist in all the three states of matter and when it is in gaseous state it is called water vapour.
The amount of water vapour present in a column of air determines the Absolute Humidity of air but this principle is not usually preferred by meteorologists. The concept of Relative Humidity is used whereby the amount of water vapour present in air is calculated with respect to the amount of water vapour the air can hold. During rainy season or conditions of high humidity, the relative humidity is on the higher side which means air cannot hold moisture further.
Human body (human being a warm blooded animal) via its hypothalamus regulates the body temperature and in high temperature conditions in the environment body tries to maintain its internal temperature by evaporating moisture from skin to the atmosphere and the evaporated moisture or sweat takes away with it specific heat and hence cools the body.
In humid conditions where surrounding air cannot hold further water vapour, sweat evaporates slowly, if at all. As a result the body heats up. it is difficult for the sweat to evaporate and in high humidity conditions we tend to sweat more.
This explains why it feels so much hotter in high humidity. When relative humidity reaches a high enough level, the body’s natural cooling system simply can’t work. Sweat evaporates very slowly, if at all, and the body heats up. Hence, it feels much hotter in humid conditions.
SAGAR CHAHAR, M.B.B.S Gurgaon, Haryana