Drbmatmosphere 160620171254

ATMOSPHERE- COMPOSITION AND STRUCTURE
Dr. Basharat Mushtaq

ATMOSPHERE- COMPOSITION & STRUCTURE DR. BASHARAT MUSHTAQ
The present condition and
properties of earth’s atmosphere
are one of the main reasons for
earth to support life
The atmosphere is the blanket
of gases or vapours that
surrounds the earth, and held
together by the force of
gravity.

Extends from a few meters below the earth’s surfaces or water’s
surface to a height of about 60,000 km. About 90% of the atmosphere
is within few km from the ground.
Most of the mass of the atmosphere is near planetary surface, as the
gravity pulls them towards the earth’s centre.
The atmosphere is a complex system in which physical and chemical
reactions are constantly taking place and many atmospheric
processes take place in a state of dynamic balance
for example; there is an average balance between the heat input to,
and output from, the atmosphere. Earth's climate system
maintains a dynamic balance between solar energy entering
and radiant energy leaving the atmosphere

GENERAL CHARECTERISTICS OF THE ATMOSPHERE
Air has weight and the pressure it
exerts is known as atmospheric
pressure.
Atmospheric pressure is a climatic element. At
sea level the pressure is 1034 gram per
square cms. (14.7pound per square inch.)
Air is colourless, odourless, and tasteless.
It is mobile, elastic, and compressible
We cannot feel its presence unless there is horizontal motion
in it…….WIND

Importance of atmosphere

Nitrogen : essential to make living matter,
nitrogen fixing bacteria and ammonia
manufacturing plants produce chemically bound
nitrogen, which is also available to the animals
Atmosphere transfers water
from the oceans due to
evaporation and transpiration.
Atmosphere constantly exchange
energy and matter with other
components of the earth – lithosphere,
hydrosphere and biosphere
Atmosphere
maintains the
level of water
and radiation
in the Earth
system

Constant gases are the ones, whose
concentrations do not change over
time, and their concentrations
almost remain same.
COMPOSITION OF ATMOSPHERE
The composition of the atmosphere are
gases present in large amounts, water
vapour and solid particles in
considerably less amounts.
Gases
constant
gases
variable
gases
Variable gases are present in different
concentrations at different places and times.

COMPOSITION OF ATMOSPHERE
Gaseous composition of the atmosphere
is usually expressed by percentage
volume, that is, each gas’s relative part
of the total mixture
Major
gaseous
composition
Trace gases
The concentration of gases in the atmosphere is
measured in parts per thousand (ppt), parts per
million (ppm) and parts per billion (ppb).

Full Name Formula % Volume # Of Parts Unit Variable? Cumulative
Volume
Nitrogen N2 78.1% 78 parts per Hundred 78.10%
Oxygen O2 20.9% 21 parts per Hundred 99.00%
Argon Ar 0.934% 9 parts per Thousand 99.93%
Water Vapor H20 0.04% 400 parts per million variable 99.97%
Carbon Dioxide CO2 0.0369% 370 parts per million 99.99%
Neon Ne 0.00182% 18 parts per Million 100.00%
Helium He 0.000524% 5 parts per Million 100.00%
Methane CH4 0.0001842% 2 parts per Million 100.00%
Krypton Kr 0.000114% 1 part per Million 100.00%
Hydrogen H2 0.0001% 1 part per million variable 100.00%
Nitrous Oxide N20 0.0000315% 315 parts per billion 100.00%
Carbon Monoxide CO 0.00002% 200 parts per billion variable 100.00%
Xenon Xe 0.0000087% 87 parts per billion 100.00%
Ozone O3 0.000005% 34 parts per billion variable 100.00%
Sulphur Dioxide SO2 0.000002% 20 parts per billion variable 100.00%
Ammonia NH3 0.000002% 20 parts per billion variable 100.00%
Formaldehyde CH20 0.000001% 10 parts per billion variable 100.00%
Nitrogen Dioxide NO2 0.0000003% 3 parts per billion variable 100.00%
Nitric Oxide NO 0.0000003% 3 parts per billion variable 100.00%
Hydrogen Sulfide H2S 0.0000002% 2 parts per billion variable 100.00%
Hydrochloric Acid HCl 0.00000015% 2 parts per billion variable 100.00%
Nitric Acid HNO3 0.0000001% 1 part per billion variable 100.00%

Methyl Chloride CH3Cl 0.00000006% 600 parts per trillion 100.00%
Freon-12 CF2Cl2 0.0000000544% 546 parts per trillion 100.00%
Carbonyl Sulfide COS 0.00000005% 500 parts per trillion 100.00%
Freon-11 CFCl3F 0.0000000263% 263 parts per trillion 100.00%
Carbon
Tetrachloride
CCl4 0.000000098% 97 parts per trillion 100.00%
Freon-113 C2F3Cl3 0.000000082% 82 parts per trillion 100.00%
Methyl Chloroform CH3CCl3 0.000000056% 47 parts per trillion 100.00%
HCFC-22 CHClF2 0.0000001525% 153 parts per trillion 100.00%
HFC-23 CHF3 0.0000000011% 23 parts per trillion 100.00%
Sulphur
Hexaflouride
SF6 0.000000004% 5 parts per trillion 100.00%
Perfluoroethane C2F6 0.000000004% 4 parts per trillion 100.00%
Triflouromethyl
Sulphur
Pentaflouride
SF5CF3 0.00000000012% .12 parts per trillion 100.00%
Sources
1. McGraw-Hill Encyclopedia of Science and Technology, 1987, McGraw-Hill, Inc.
2. Carbon Dioxide Information Analysis Center

The gaseous area surrounding the planet is divided into
several concentric strata or layers. About 99% of the
total atmospheric mass is concentrated in the first 20
miles (32 km) above Earth’s surface.
There are two types of atmospheric structures such as:
1. Thermal structure
2. Magneto-electronic structure.
Structure of Atmosphere

Atmospheric layers are
characterized by variations in
temperature resulting primarily
from the absorption of solar
radiation;
• visible light at the surface,
• near ultraviolet radiation in the
middle atmosphere, and
• far ultraviolet radiation in the
upper atmosphere.
THERMAL STRUCTURE

THERMAL STRUCTURE OR Vertical structure of Atmosphere
Exosphere
Thermosphere
Mesosphere
Stratosphere
Troposphere

Bottom layer of the atmosphere
70% mass of the atmosphere
Extends to an average height of 5-20 km
Thickness varies with latitude:
poles about 8 km; about 16 km above the equator
Temperature decreases with height in this layer
The rate of decrease of temperature with altitude is called, lapse rate.
Average lapse rate in troposphere is -6.4 °C / km
Troposphere ends at tropopause. Tropopause is just like a lid over the troposphere,
where temperature stops decreasing with height
Troposphere

Second lowest layer of atmosphere. Very little weather occurs
Extends above the tropopause to an altitude of about 30 miles (50 km) above the
planet’s surface.
Temperature inversion occurs in Stratosphere, Temperature increases as a result of
interactions between high energy UV radiation and ozone (O3)
Ozone absorbs the bulk of solar ultraviolet radiation in wavelengths from 290 nm – 320
nm (UV-B radiation)
Stratopause Where the temperature reaches a maximum of 10 OC
Stratosphere

On the average, the
temperature decreases about
6.5OC/1,000 km, which is
known as the observed lapse
rate.
An inversion is a layer of air
in which the temperature
increases with height.

The mesosphere a layer extending from
approximately 30 to 50 miles (50 to 85 km)
above the surface
Characterized by decreasing temperatures
The coldest temperatures in Earth’s atmosphere
occur at the top of this layer, the mesopause
The stratosphere and mesosphere together are
sometimes referred to as the middle atmosphere.
Mesosphere

The thermosphere is located above 80 km from
earth
The temperature in the thermosphere
generally increases with altitude reaching
600 to 3000 F (600-2000 K) depending on
solar activity.
Above 60 miles (100 km) from Earth’s surface
the chemical composition of air becomes
strongly dependent on altitude and the
atmosphere becomes enriched with lighter
gases (atomic oxygen, helium and hydrogen).
Very little energy transfers, however, due to the
lack of molecules (very few molecules to collide
with objects)
Thermosphere

The exosphere is the most
distant atmospheric region
from Earth’s surface
The altitude of its lower boundary, known
as the thermopause or exobase, ranges
from about 150 to 300 miles (250-500
km) depending on solar activity
The exosphere is a transitional zone
between Earth’s atmosphere and
interplanetary space
Exosphere

The upper atmosphere is
also divided into regions
based on the behaviour
and number of free
electrons and other
charged particles
MAGNETO-ELECTRONIC STRUCTURE
 Ionosphere
 Plasmasphere
 Magnetosphere

The ionosphere is defined by atmospheric effects on radiowave propagation as a result
of the presence and variation in concentration of free electrons in the atmosphere
Ionosphere
D-region is about 35 to 55 miles (60 - 90 km) in altitude
but disappears at night.
E-region is about 55 to 90 miles (90 - 140 km) in altitude.
F-region is above 90 miles (140 km) in atitude. During the
day it has two regions known as the:
o F1-region from about 90 to 115 miles (140 to 180 km)
altitude
o F2-region in which the concentration of electrons peaks in the
altitude range of 150 to 300 miles (around 250 to 500
km).

image: regions of ionosphere)

The plasmasphere is not really spherical but a doughnut-shaped region (a torus)
with the hole aligned with Earth’s magnetic axis.
The Earth’s plasmasphere is made of just that, a plasma, the fourth state of matter.
This plasma is composed mostly of hydrogen ions (protons) and electrons. It has
a very sharp edge called the plasmapause
The plasmasphere is essentially an extension of the ionosphere. Inside of the
plasmapause, geomagnetic field lines rotate with the Earth.
Plasmasphere

Extension of plasmasphere)

Magnetosphere
The magnetosphere is a cavity (also not spherical) in which the
Earth’s magnetic field is constrained by the solar wind and
interplanetary magnetic field (IMF).
The outer boundary of the magnetosphere is called the magnetopause.
The magnetosphere is shaped like an elongated teardrop (like a Christmas Tree
ornament) with the tail pointing away from the Sun

The magnetopause is typically located at about 10 Earth radii or some
35,000 miles (about 56,000 km) above the Earth’s surface on the day
side and stretches into a long tail, the magnetotail, a few million
miles long (about 1000 Earth radii)
Beyond the magnetopause are the magnetosheath and bow
shock which are regions in the solar wind disturbed by the
presence of Earth and its magnetic field

Drbmatmosphere 160620171254

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