Five layers of Atmosphere defined for layman, The upper layer of the earth above the ground is air which is composed of different gases and water vapours. This whole layer of air is called atmosphere. The amount of gases in the atmosphere is different; nitrogen is present in highest percentage that is 78.09% oxygen is the second most abundant gas that is 20.95%, Argon is 0.93%, carbon dioxide is 0.04% and traces of some other gases are also found.
The atmosphere as we see it, is not a single layer but instead it is made up of 5 layers or strata. They are; troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
Troposphere is the lowest layer of earth atmosphere. It contains gases like nitrogen, oxygen, argon, carbon dioxide and some small amount of other gases. It is the layer of the atmosphere in which the water vapour are abundant, therefore all the weather related activities are observed in this layer. The environmental lapse rate (ELS) is negative in this strata, meaning that the temperature decreases with the altitude. It ends in the tropopause.
Above the troposphere is stratosphere. It is separated from the troposphere by a boundary called the tropopause. It is the strata in which ozone layer is present. The ELR in this strata is positive. The reason for this is that the ultra violet radiations are absorbed by the ozone in this layer which makes the temperature rise. The ending boundary of this strata is called stratopause.
Next to the stratosphere is the third strata of the earth atmosphere called the mesosphere. The ELR become negative in this strata. The ending boundary of this strata is called the mesopause, due to the ELR phenomenon since the mesopause is the highest region in this layer so it is also the coldest region.
Next to the mesosphere is the widest layer of the earth called, the thermosphere. It is the second last layer of the atmosphere. It is the layer in which ionosphere is formed ( by photo-ionization caused by the UV radiation). Since to this strata the solar winds can reach thus auroral zones are also found here. The ELR is positive in this strata, that is with increase in altitude, there is an increase of temperature observed. Its ending regions is called thermopause.
It is the outer most layer of the earth atmosphere. The temperature in this strata increases with altitude. The density of this strata is very low. The non-hydrometerological phenomena (like aurora australis and aurora borealis, explained in next article) are observed here. This strata is totally vapour and water free.
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