CAN ACADE
TT MY
Bhatti Street Near Mann–o–Salwa Tulsa Road Lalazar Rwp Ph: 051-8442595, WE OWN OUR STUDENTS
5122139, Cell: 0345-5930370
CHAPTER-NO-14
ENVIRONMENTAL CHEMISTRY –I ATMOSPHERE
Atmosphere: The envelope of gases and water vapors surrounding the planet earth is called atmosphere.
Layers of atmosphere: There are four major layers of atmosphere.
i) The Troposphere ii) The Stratosphere
iii) The Mesosphere iv) The Thermosphere
The Troposphere:-
It is the first layer around the surface of earth. It extends to about 12 kilometer above the surface of
earth. It is the layer which is closest to the surface of earth. It is the layer in which we live nearly all the
dust particles and vapours are present in this layer. Most of the clouds are formed in this layer. Air craft
fly in this layer. Tropo-means turning or changing. Therefore the condition in this layer changes
regularly. As the attitude increase in this layer then the temperature decreases from 170 to -550 C.
for every 1km increase in attitude the temperature of air gets 6.50 cooler.
The Stratosphere:-
It is the second layer around the surface of earth. This layer extends from top of the troposphere to about
50km above the surface of earth.
Stratosphere is further divided into two parts.
i) Lower stratosphere. ii) Upper Stratosphere.
The lower stratosphere is cold about -550C but the upper stratosphere is warmer than the lower
stratosphere. Ozone is present in upper stratosphere and this ozone is responsible for the rise in
temperature. Ozone saves us from harmful effects of ultraviolet radiation coming from the sun. When
ozone absorbs energy from the sun then this energy is converted into heat. Due to this heat the
temperature in stratosphere increases. The temperature in the stratosphere varies -550 to -50C.
The Mesosphere:-
It is the third layer around the surface of earth. It extends from top of stratosphere to about 80km from
the surface of earth. Meso-means middle so, mesosphere is the middle layer of the atmosphere. In outer
part of mesosphere the temperature decreases up to -930C. this layer protect the surface of earth from
being hit by meteoroids.
The Thermosphere:-
It is the outer most layer of the atmosphere. It extends from 80km above the surface of earth and goes into
space. Thermo- means heat. Temperature in this layer is very high and it reaches up to 1800 0C. The oxygen
and nitrogen molecules convert the solar energy into heat. As a result, the temperature increases up to 800 0C.
Thermosphere is further divided into two layers.
i) Ionosphere ii) Exosphere
i) Ionosphere:
The lower part of the thermosphere is called ionosphere. It extends from 80km to four hundred
kilometer/ 400km above the surface of earth.
TT MY
Bhatti Street Near Mann–o–Salwa Tulsa Road Lalazar Rwp Ph: 051-8442595, WE OWN OUR STUDENTS
5122139, Cell: 0345-5930370
CHAPTER-NO-14
ENVIRONMENTAL CHEMISTRY –I ATMOSPHERE
Atmosphere: The envelope of gases and water vapors surrounding the planet earth is called atmosphere.
Layers of atmosphere: There are four major layers of atmosphere.
i) The Troposphere ii) The Stratosphere
iii) The Mesosphere iv) The Thermosphere
The Troposphere:-
It is the first layer around the surface of earth. It extends to about 12 kilometer above the surface of
earth. It is the layer which is closest to the surface of earth. It is the layer in which we live nearly all the
dust particles and vapours are present in this layer. Most of the clouds are formed in this layer. Air craft
fly in this layer. Tropo-means turning or changing. Therefore the condition in this layer changes
regularly. As the attitude increase in this layer then the temperature decreases from 170 to -550 C.
for every 1km increase in attitude the temperature of air gets 6.50 cooler.
The Stratosphere:-
It is the second layer around the surface of earth. This layer extends from top of the troposphere to about
50km above the surface of earth.
Stratosphere is further divided into two parts.
i) Lower stratosphere. ii) Upper Stratosphere.
The lower stratosphere is cold about -550C but the upper stratosphere is warmer than the lower
stratosphere. Ozone is present in upper stratosphere and this ozone is responsible for the rise in
temperature. Ozone saves us from harmful effects of ultraviolet radiation coming from the sun. When
ozone absorbs energy from the sun then this energy is converted into heat. Due to this heat the
temperature in stratosphere increases. The temperature in the stratosphere varies -550 to -50C.
The Mesosphere:-
It is the third layer around the surface of earth. It extends from top of stratosphere to about 80km from
the surface of earth. Meso-means middle so, mesosphere is the middle layer of the atmosphere. In outer
part of mesosphere the temperature decreases up to -930C. this layer protect the surface of earth from
being hit by meteoroids.
The Thermosphere:-
It is the outer most layer of the atmosphere. It extends from 80km above the surface of earth and goes into
space. Thermo- means heat. Temperature in this layer is very high and it reaches up to 1800 0C. The oxygen
and nitrogen molecules convert the solar energy into heat. As a result, the temperature increases up to 800 0C.
Thermosphere is further divided into two layers.
i) Ionosphere ii) Exosphere
i) Ionosphere:
The lower part of the thermosphere is called ionosphere. It extends from 80km to four hundred
kilometer/ 400km above the surface of earth.
