Lecture 2 Atmosphere – its composition, extent and structure (English

Atmosphere – its composition, extent and structure

Atmosphere

The atmosphere is a multilayer gaseous envelope covering the earth from all sides, whose total mass istons and its height above sea level is estimated from 16 to 29 thousand kilometers. Its mass density decreases with height.

ü  The atmosphere provides essential gases, heat, and water for all the plants and animals of the biosphere, due to which the earth has become a habitable area for all living beings.

ü  It absorbs the ultraviolet rays coming from the sun and prevents them from coming on the surface of the earth, thus the surface is saved from overheating.

v  Composition of Atmosphere

1.   Gases

2.   Water vapor

3.   Suspended particulate matter or aerosols

v  Gases

1.   Constant/permanent gases

2.   Variable Gases

v  Constant/permanent gases

ü  Nitrogen in the atmosphere is 78.1, oxygen 20.9, argon 0.9 percent.

ü  The ratio of these gases remains constant till the lower part of the atmosphere or the height of 80 km.

ü  Nitrogen is found in the atmosphere in 7 forms

1.   Nitrous oxide

2.   Elemental nitrogen

3.   Ammonia

4.   Nitrous acid

5.   Nitric oxide (NO)

6.   Amino acids

7.   Nitrogen peroxide (NH)

ü  Nitrogen is essential for all living beings because it is the main component of amino acids for protein formation. Nitrogen is found most in the atmosphere, yet living beings are not able to take it directly.

ü  Nitrogen cycle takes place in the biosphere which is completed in the following steps

1.   Fixation of atmospheric nitrogen in the roots of pulse plants by bacteria found in the soil.

2.   Mineralization of fixed nitrogen in the soil by the processes of ammonification and nitrification.

3.   As a result of which plants take in the form of ammonium ion or nitrate ion.

4.   Addition of elemental nitrogen to the atmosphere by denitrification.

v  Ammonification: - The process of decomposition of nitrogenous organic matter with the production of ammonia or ammonium compounds by the action of bacteria is called ammonification.

v  Mineralization: - Mineralization is a process in which an inorganic material is precipitated into an organic material. It can be due to normal biological processes occurring during the life of an organism like formation of bones, formation of egg shells, Formation of teeth etc.

v  Nitrification: - Oxidation of ammonia or ammonium gives it a cloud in nitrate or nitrite, it is called nitrification.

v  Oxygen

Atmospheric oxygen is a very active gas, it is also called the vital air of living beings and it plays an important role in the formation of carbohydrate, fat and protein in their body. It is found in the atmosphere up to a height of 60 km. It happens.

     2. Variable gases under this

1.   Carbon dioxide (Co2)

2.   Ozone (O2)

3.   hydrogen (H2)

4.   Helium (He)

5.   Nian (Ne)

6.   Xenon (X2)

7.   Krypton (Kr)

8.   Methane (Me)

ü  The amount of CO2 is less in the atmosphere, it is very important in the development and origin of living beings on the earth, due to which the process of photosynthesis is possible.

ü  CO2 is transparent to the solar radiations entering the atmosphere but opaque to the outgoing solar radiations resulting in green effect.

ü  The risk of global warming is increasing as a result of increasing concentration of CO2 due to ongoing industrial activities.

ü  The presence of ozone (O3) is especially important for all flora and fauna because its layer acts as a shield to protect the earth's living beings from solar ultraviolet rays.

ü  Nowadays, due to the emission of greenhouse gases such as chlorofluorocarbons, the ozone layer is getting eroded.

ü   Ozone gas is mostly found in the atmosphere at an altitude of 10-15 km.

2.   Water vapor

ü  Water vapor present in the atmosphere is an important component of the atmosphere because it is responsible for the saturation, condensation and precipitation of various forms of moisture in the atmosphere such as snow, sleet, sleet, rain, fog and condensation water etc. The construction process is over.

ü  The main sources of water vapor in the atmosphere are evaporation from the surface of land and underground water bodies like oceans, rivers, drains, reservoirs, etc. and transpiration from the vegetation present on the land.

ü  These water vapors are present in the atmosphere in the form of hygroscopic water by the action of adsorption with particulate matter such as dust particles etc. which are held under water potential ranging from -10000 bar to -31 bar i.e. atmospheric pressure which is present in the atmosphere. As a result of the process of saturation, condensation and formation of water drops in some part of the water, it takes the form of rain.

ü   More than 90% of the total water vapor in the atmosphere is found up to a height of 5 km from the sea level. If the entire amount of water vapor in the atmosphere is condensed, then a surface of 2.5 cm pearl water will be formed around the earth.

3. Suspended particulate matters or aerosols

ü  Sticks to suspended particulate matter present in the atmosphere such as dust particles, rock particles from weathering of rocks, meteor rays, ash particles from volcanoes, salt particles from ocean surfaces and organic matter such as bacteria, pollen grains, microscopic seeds Water droplets are collectively called aerosols.

ü  Their quantity decreases with height.

v  Structure of atmosphere: - Structure of the atmosphere

ü  The atmosphere is a structure with several concentric layers or regions, these layers are also called sub spheres.

  Structure of Atmosphere