In primary School, we would define the atmosphere as a“ blanket covering the Earth” but in general it is defined as a layer of gases that surrounds the earth , I like to define it as the source of life ,that is to say there would not be life without the atmosphere . The atmosphere insulates the Earth from extreme temperatures; it keeps heat inside the atmosphere and it also blocks the Earth from much of the Sun's incoming ultraviolet radiation (NASA 1999).
The Earth’s atmosphere is divided into four different layers , namely , the Troposphere , Stratosphere , Mesosphere and the Thermosphere, In this essay , I am going to explain , with the aid of a diagram the layered structure of the atmosphere, the different temperatures that occur and also the different processes that take place in all the layers.

layered structure of atmosphere
As you can see in this picture above, this is how the layers are positioned in the atmosphere, it starts with the Troposphere which is the bottom layer and the one closest to the Earth ,it is the most important layer because all life takes place here, the important gases which are essential for living are found only here , it has a height of 12km, almost all weather occurs in this layer, the air is warmer at bottom of the troposphere and as you go up it gets cooler until eventually it reaches a point of dryness because altitude varies with latitude All the different layers have boundaries that separate them, in the troposphere it is called the tropopause ,the tropopauses separates the troposphere from the stratosphere which is the layer above and it is where the temperature declines , this rate of decline is known the lapse rate. The tropopause is not a complete barrier, it leaks. Strongly convective tropospheric storms transport water vapour up across the tropopause. There are breaks in the tropopause near jet stream westerlies allowing interchange of stratospheric and tropospheric air.(Atmospheric optics: 2014).In summary , the troposphere is considered to be the most important layer to humans , animals and plants because of all the essential needs it provides. The layer following the troposphere is the Stratosphere, it occupies the central region of the atmosphere , I personally consider this layer to be the second most important layer , mainly because it contains ozone layer which a layer that blocks the sun’s ultraviolet radiation from entering into the Earth .the ozone layer is very important to human, plant and animal life , imagine life without the ozone layer , it would be impossible for endless reasons , this introduces us to the term ‘’ozone depletion’’ , this is depletion or destruction of the ozone layer caused by the release of several manufactured chemicals , the depletion of the ozone layer creates a hole , allowing more UV radiation to enter the earth ,causing following impacts : Harm to human health, Adverse impacts on agriculture, forestry and natural ecosystems, Damage to marine life, eye and skin cancer in Animals, degradation of construction Materials(BC AIR QUALITY 2013).Unlike the troposphere , the stratosphere’s temperature increases with height ,which is 50 km , No weather occurs in this layer because the clouds are rare, the boundary that separates the stratosphere from the next layer which is the mesosphere is called the Stratopause., the stratosphere is quite an important layer ,it is very important that we take care of if by increasing the oxygen and decreasing CFCs in the air by planting more trees to keep our earth from further or total ozone depletion (Buzzle 2012).
The next layer is the mesosphere , this layer is above the troposphere , the temperature here decreases with height until it reaches the mesopause which is the area separating it from the next layer, it lies at an altitude of 50 to 80 km. both the stratosphere and mesosphere form the central region of the atmosphere and the mesosphere is also the second outermost layer .the mesosphere has clouds known as Noctilucent that appear as wispy clouds that only occur during the night , they look like the reflection of sunlight from meteoric dust particles coated with ice crystals , they are very beautiful clouds and they can be seen from the poles.