Editing Content :: Admin Scraper

Chapter

Content type

Position

Value

C H A P T E R C OMPOSITION AND S TRUCTURE OF A TMOSPHERE an a person live without air? We eat Gases foodtwo-threetimesadayanddrink C water more frequently but breathe Carbon dioxide is meteorologically a very every few seconds. Air is essential to the important gas as it is transparent to the survival of all organisms. Some organisms like incoming solar radiation but opaque to the humans may survive for some time without outgoing terrestrial radiation. It absorbs a part of terrestrial radiation and reflects back some food and water but can’t survive even a few part of it towards the earth’s surface. It is minutes without breathing air. That shows the largely responsible for the green house effect. reason why we should understand the The volume of other gases is constant but the atmosphere in greater detail. Atmosphere is a volume of carbon dioxide has been rising in mixture of different gases and it envelopes the the past few decades mainly because of the earthallround.Itcontainslife-givinggaseslike burning of fossil fuels. This has also increased oxygen for humans and animals and carbon dioxide for plants. The air is an integral part ofe temperatur e of the air. Ozone is another important component of the atmosphere found the earth’s mass and 99 per cent of the total between 10 and 50 km above the earth’s mass of the atmosphere is confined to the surface and acts as a filter and absorbs the height of 32 km from the earth’s surface. The ultra-violet rays radiating from the sun and air is colourless and odourless and can be felt prevents them from reaching the surface of the only when it blows as wind. earth. Can you imagine what will happen Water Vapour to us in the absence of ozone in the atmosphere? Water vapour is also a variable gas in the atmosphere, which decreases with altitude. In the warm and wet tropics, it may account for four per cent of the air by volume, while in the C OMPOSITION OF THE A TMOSPHERE dry and cold areas of desert and polar regions, The atmosphere is composed of gases, water it may be less than one per cent of the air. vapour and dust particles. The proportion of gases changes in the higher layers of the Water vapour also decreases from the equator towards the poles. It also absorbs parts of the atmosphere in such a way that oxygen will be insolationfromthesunandpreservestheearth’s almost in negligible quantity at the height of radiated heat. It thus, acts like a blanket 120 km. Similarly, carbon dioxide and water allowing the earth neither to become too cold vapour are found only up to 90 km from the nor too hot. Water vapour also contributes to surface of the earth. the stability and instability in the air. Reprint 2026-27