Environmental Segments

Environmental segments
The environmental segments are following below
1. Atmosphere
2. Hydrosphere
3. Biosphere
4. Lithosphere

Atmosphere

The cover of air that envelopes the earth is known as the atmosphere. It is the protective thick gaseous mantle, surrounding the earth, which sustais life on earth and save it from unfriendly environment of outer surface.

Characteristics of atmosphere
1. Weight :( 4.5 to 5) ×105 metric ton.
2. Pressure : 1 atm. to 3× 107 at 100 km above sea level.
3. Temperature:-100 to 1200 °C, depending on altitude.
4. Density : 0.0013 gm/m3

The atmosphere protects the earth from dangerous cosmic radiations. It screens the dangerous radiations from the sun (< 300 nm ) and transmit only 300 nm – 2500 nm radiations. It plays a vital role in maintaining the heat balance on earth by absorbing radiation from sun and earth.


The Atmospheric Structure

Name of the Region Height of the earth
(km) Temperature,°C Major chemical species
Troposphere 1 to 11 15 to -56 O2, N2, CO2, H2O
Stratosphere 11 to 50 -56 to -2 O3
Mesosphere 50 to 85 -2 to -92 O2+ , NO+
Thermosphere 85 to 500 -92 to 1200 O2+ , NO+, O+



Troposphere

This is the nearest region to earth’s surface and extends up to on altitude an altitude of 11 km.

Characteristics
• It is account for over 70% of the total atmospheric mass.
• The temp. of air in this region decreases exponentially with increasing altitude.
• The temperature rages 15 to -56 °C.
• The top of troposphere is troposphere, it makes temp. Inversion.
• Major chemical species are O2, N2, CO2, and H2O.


Stratosphere


The region above tropopause is called stratosphere.
Characteristics
• Height above the earth surface ranges from 11 to 50 km.
• Temperature ranges -56 to -2 °C.
• Due to its low temperature, clouds, dust and water vapor is absent in this region.
• Major chemical species O3.
• The temperature rises with increasing altitude.
• The top of stratosphere is stratopause.





Mesosphere
It is the region above the trapause , it extends up to 85 km height.
Characteristics
• Here temperature decreases with height.
• The decrease in temperature is due to low absorption of UV radiation by ozone.
• Temperature ranges from -2 to -92 °C.
• Mesosphere is the coldest region of atmosphere.
• Major chemical species are O2+, NO+, O+, and N2.
• The layer immediately above the mesosphere is mesospause.

Thermosphere
It is the region immediately above the mesospause.
Characteristics
• The Temperature rises very rapidly with increasing altitude.
• The Temperature ranges from -92 to 1200 °C.
• It extends up to 85 to 500 km.
• It has lower pressure and low density.
• Major chemical species are O2+, NO+, and O+.