ATMOSPHERE

 

ATMOSPHERE:-

 

The Earth Is Surrounded By Blanket Of Air, Which We Call Atmosphere. It plays a significant role in the life of living organisms on earth. Without atmosphere a living organism cannot survive on earth. Hence, it is an important nature resource.

Atmosphere extends over 690 kilometers from the surface of the earth. It helps living organisms by, providing important gases to them, protecting them from ultraviolet rays, by providing rainfall, it helps in controlling the global warming and it acts like a protector for the earth.   

 

Atmosphere is a mixture of various gases and dust particles. It mainly consists of 78% of nitrogen, 20.9% of oxygen 1% of argon, carbon dioxide and other gases. The atmosphere will be denser in the lower surface of the earth the upper layer. We can also say that decrease in altitude, decrease in density of air and vise-versa.

There will be increase in density of air as we increase the altitude because in higher altitudes the upper layer pushes the air towards the down layer. This is the reason why it is difficult to breath as we go to higher altitudes.

Atmosphere pressure depends on three main factors:


1. Atitude          2. Temperature         3. Water vapour 


(1)  Altitude- The preasure of the air deacreases. At a rate of 1cm for every 110metres of ascent.


(2)Temperature- When the temperature rises,air expands. At the Equator as the area gets direct rays of sun.

 

(3) Water Vapour- Air containing water vapour is lighter than dry air. The more water vapor, the lighter the air.

 

STRUCTURE OF ATMOSPHERE




Troposphere

Stratosphere

Mesosphere

Ionosphere/Thermosphere

Exosphere

(1) Troposphere

                            The term troposphere literally means the region of mixing. It has been derived from the Greek word tropos meaning mixing or turbulence. The average height of troposphere is about 14Km above sea level. It is the lowermost atmospheric layer closest to the earth. The degree at which water vapour is present in air is called humidity.

 

(2) Stratosphere

                           The lowermost limit of stratosphere is at tropopause .This layer is free of water vapour and dust. It extends from 15 to 50Km  between  50  to 60 latitudes. In this layer, the temperature does not change with latitude.  The stratosphere is that it contains the ozone layer. There is maximum concentration of ozone, a vital gas between 20-30Km. This region is called ozonosphere.

(3) Mesosphere

                           This layer lies from 50 to 80 Km above the earth’ surface. Meteors from space mostly burn up in this layer, creating shooting stars.

 

(4) Ionosphere/Thermosphere

                           Ionosphere extends from 80Km to about 450 Km. Ionosphere reflects the low frequency radio waves, but absorbs the median and high frequency waves. Thus, this layer is especially important in long distance radio communication.

 

(5) Exosphere

                         This outermost layer of atmosphere forms the outermost boundary of our atmosphere. The atmosphere in this region is highly predominant with rarified hydrogen and helium.

 











 

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