This document provides information about the coordinates of India and Tamil Nadu, the composition and layers of the atmosphere, and uses of the atmosphere. It describes the vertical layers of the atmosphere based on temperature, including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The troposphere extends from the Earth's surface to around 16 km and is where weather occurs. Temperature decreases with height in the troposphere at the average lapse rate of 6.5°C per km.

1. Lec - 2
 Coordinates of India & Tamil nadu
 Atmosphere
 Uses of Atmosphere
 Composition of atmosphere
 Vertical layers of atmosphere lapse rate

2. India Latitude 08º 40’ N & 37º 60’ N
Longitude 68º 07’ E & 97º 25’ E
Tamil Nadu Latitude 08º 04’ N & 13º 35’ N
Longitude 76º 15’ E & 80º 20’ E
Coordinates

3. Earth is elliptical has three spheres
• Hydrosphere
• Lithosphere
• Atmosphere

4.  Colourless, odourless and tasteless physical mixture of
gasses which surrounds earth on all sides
 Mobile, compressible and expandable
 Contains huge number of solid & liquid particles called
aerosol.
 Some gases are permanent atmospheric constituents in
fixed proportions
 Others vary from place to place and time to time.
 Lower atmosphere where the chemical composition of gas
is uniform is called homosphere.
 Higher levels the chemical composition of air changes
considerably and known as heterosphere.
Atmosphere

5.  Provides O2 for respiration, CO2 to build biomass in
photosynthesis & nitrogen essential for plant growth.
 Acts as a medium for transportation of pollen.
 Protects crops plants on earth from harmful U.V.rays.
 Maintains warmth to plant life and
 Provides rain to field crops as it is source of water
vapour, cloud, etc.
Uses of atmosphere

6. N2 78.08 O2 20.95 Ar 0.93
CO2 0.03 Ne 0.0018 He 0.0005
CH4
0.00017 H2 0.00006 O3 0.00004
Composition of atmosphere (% by volume)

7. Vertical Layers of atmosphere based on temperature
Mesopause
Stratopause
100
20ºC
Thermosphere
Mesosphere
Upper Stratosphere
Tropopause
Troposphere
Temperature (ºC)
Height
(Km)
10
20
30
40
50
60
70
80
90
0ºC
-20ºC
-40ºC
-60ºC
-80ºC
-100ºC
1000ºC
Lower Stratosphere

8.  “Trop” means mixing or turbulence (sphere-region)
 Height 14 km above MSL -16 km at equator 7-8 km
at poles
 Layer is called as “seat of weather phenomena”.
 Wind velocities increase with height and attain the
maximum at the top of this layer.
 Decrease of temperature with increasing elevation
at a mean lapse rate of about 6.5°C per km.
Troposphere

9. Cont…
 Radiation received from sun is absorbed by the
earth’s surface & so the troposphere is heated
from below.
 About 75 per cent of total gases and most of the
moisture and dust particles present.
 A shallow layer separates it from stratosphere
known as “Tropopasue “ is a transitional zone
with no air movement

10.  Exists above tropopause and extends to altitudes of
about 50-55 km
 Seat of photochemical reactions or Ozonosphere
 Temperature increases with height , depends upon
troposphere
 Upper parts the temperature is like the earth’s surface
due to the absorption of UV radiation by ozone in this
region
 Less convection takes place because it is warm at top
and cold at bottom
 Upper boundary of stratosphere is called as
‘stratopause’
Stratosphere

11.  Maximum concentration of O3 between 30-60 km
 Because of chemical process this sphere is called
as the “chemosphere”
 Temperature decreases with height & upper
boundary is “Mesospause”
 Mesosphere is the coldest region in the
atmosphere with temperature reaching the lowest
value (-95°C) at the mesopause (80km)
Mesosphere

12.  Lies beyond mesosphere at a height of 80 km and
extends upto 400 km.
 Known as ionosphere due to enriched ion in
distinct ionised layers
 The temperature increases again and is in the
order of 1000°C.
 Long distance radio communication is possible
Thermosphere

13.  Outer most layer of earth’s atmosphere
 Exosphere lies between 400 and 1000 km.
 Density of gases is extremely low.
 H2 and He gases predominate
 About 500 to 600 km, the density becomes so low
Exosphere

14.  Rate of change of temperature in an ascending or
descending air mass through adiabatic process is
called as adiabatic lapse rate.
 Thermodynamic transformation which occurs without
exchange of heat between a system and its
environment is known as adiabatic process.
 Adiabatic cooling accompanies expansion and
adiabatic warming accompanies compression.
Lapse rate
Decrease in air temperature with height (6.5°C/km)
Adiabatic lapse rate