UGC NET Paper 1 Mathematical Reasoning & Aptitude.pdf
Chapter 4 global atmosphere change
1. CHAPTER 4: Global Atmosphere
Change
Prepared by: Shaheen Sardar
COURSE TITLE: Environmental issues of textile
industry
2. THE ATMOSPHERE OF THE EARTH
• The atmosphere is made up almost entirely of
Nitrogen and Oxygen, other gases and particles
existing in very small concentrations determine to
a large extent the habitability of the earth.
• These other gases are CO2, Nitrous oxide (N2O),
Methane (CH4), and Ozone (O3) as well as a
category of human made gases called
“halocarbons” that includes chlorofluorocarbons
(CFCs), hydro-chlorofluorocarbons (HCFCs),
hydro-fluorocarbons (HFCs), carbon tetrachloride
(CCl4), methyl-chloroform (CH3 CCl3), and halons.
3. THE ATMOSPHERE OF THE EARTH
• Concentrations of most of the gases are
essentially unchanging. But CO2, CH4, and N2O
are rising.
• Following is the composition of clean, Dry air
(fraction by volume in troposphere, 1994)
4. Constituent Formula
Percent by
volume
Parts per
million (ppm)
Nitrogen N2 78.08 780,800
Oxygen O2 20.95 209,500
Argon Ar 0.93 9300
Carbon dioxide CO2 0.035 358
Neon Ne 0.0018 18
Helium He 0.0005 5.2
Methane CH4 0.00017 1.7
Krypton Kr 0.00011 1.1
Nitrous oxide N2O 0.00003 0.3
Hydrogen H2 0.00005 0.5
5. THE ATMOSPHERE OF THE EARTH
LAYERS OF EARTH:
• According to temperature, earth’s four layers
are troposphere, stratosphere, mesosphere,
and thermosphere. These layers are described
below.
6. LAYERS OF EARTH
(1) Troposphere:
• The first layer is called the troposphere. The
depth of this layer varies from about 8 to 16
kilometers. Greatest depths occur at the
tropics where warm temperatures cause
vertical expansion of the lower atmosphere.
7. Troposphere
• From the tropics to the Earth's Polar Regions
the troposphere becomes gradually thinner.
The depth of this layer at the poles is roughly
half as thick when compared to the tropics.
Average depth of the troposphere is
approximately 11 kilometers.
8. Troposphere
• More than 80% of the mass of the
atmosphere and all of the water vapor, clouds,
and precipitation occur in troposphere.
Maximum air temperature also occurs near
the Earth's surface in this layer.
9. Troposphere
• With increasing height, air temperature drops
uniformly with altitude at a rate of
approximately 6.5° Celsius per 1000 meters.
This phenomenon is commonly called the
Environmental Lapse Rate. At an average
temperature of -56.5° Celsius, the top of the
troposphere is reached. At the upper edge of
the troposphere is a narrow transition zone
known as the tropopause.
10. LAYERS OF EARTH
(2) Stratosphere:
• Stratosphere is a stable layer of very dry air.
Pollutants that find their way into the
stratosphere may remain there for many years
before they eventually drift back into the
troposphere, where they can be more easily
diluted and ultimately removed by settling or
precipitation.
13. Stratosphere
• In the Stratosphere short wavelength
ultraviolet energy is absorbed by Ozone (O3)
oxygen (O2), causing air to be heated.
• Above the tropopause is the stratosphere.
This layer extends from an average altitude of
11 to 50 kilometers above the Earth's surface.
14. Stratosphere
• The stratosphere contains about 19.9 % of the
total mass found in the atmosphere. Very little
weather occurs in the stratosphere. The
troposphere and stratosphere combined
account for 99.9% of the mass of the
atmosphere.
15. Stratosphere
• Occasionally, the top portions of
thunderstorms breach this layer. The lower
portion of the stratosphere is also influenced
by the polar jet stream and subtropical jet
stream.
• In the first 9 kilometers of the stratosphere,
temperature remains constant with height. A
zone with constant temperature in the
atmosphere is called an isothermal layer.
16. Stratosphere
• From an altitude of 20 to 50 kilometers,
temperature increases with an increase in
altitude. The higher temperatures found in
this region of the stratosphere occurs because
of a localized concentration of ozone gas
molecules. These molecules absorb ultraviolet
sunlight creating heat energy that warms the
stratosphere.
17. Stratosphere
• Ozone is primarily found in the atmosphere at
varying concentrations between the altitudes
of 10 to 50 kilometers. This layer of ozone is
also called the ozone layer.
• The ozone layer is important to organisms at
the Earth's surface as it protects them from
the harmful effects of the sun's ultraviolet
radiation. Without the ozone layer life could
not exist on the Earth's surface.
18. LAYERS OF EARTH
(3) Mesosphere:
• Separating the mesosphere from the
stratosphere is a transition zone called the
stratopause.
• In the mesosphere, air mixes fairly readily.
• In the mesosphere, the atmosphere reaches
its coldest temperatures (about -90° Celsius)
at a height of approximately 80 kilometers.
19. Mesosphere
• At the top of the mesosphere is another
transition zone known as the mesopause.
• The temperature of the atmosphere decreases
with altitude, until the Thermosphere is
reached.
20. LAYERS OF EARTH
(4) Thermosphere:
• Then, next layer is thermosphere. Heating of
thermosphere is due to the absorption of
solar energy by atomic oxygen.
• Thermosphere is exceptionally hot.
• The last atmospheric layer has an altitude
greater than 80 kilometers and is called the
thermosphere.
21. Thermosphere
• Temperatures in this layer can be as high as
1200°C. These high temperatures are
generated from the absorption of intense
solar radiation by oxygen molecules (O2).
• Measuring the temperature of thermosphere
with a thermometer is a very difficult process.
22. GLOBAL TEMPERATURE
• The average global temperature has risen in
the past 150 years.
• The period from 1961 to 1990 is the
comparison point for this graph. This is
represented by the horizontal line at 0. The
anomaly, or variation from this average, is
shown for each year.
24. THE GREEN HOUSE EFFECT
• Have you ever been inside a greenhouse?
Greenhouses are very warm inside all year round
— this is how plants are grown inside them, even
in the winter.
• The way a greenhouse works is that the glass
allows the sun's rays to shine in, but then
prevents the heat from escaping once it is inside.
• Now, think of the Earth as being a giant
greenhouse.
25. THE GREEN HOUSE EFFECT
• The gases on Earth act just like the glass; this
is how the Earth gets warm from the sun even
though it is about 93 million miles away.
• The gases allow the sun's rays to shine in, but
then prevent the heat from escaping the
Earth.
27. THE GREEN HOUSE EFFECT
• This way of warming the Earth's surface is
referred to as the greenhouse effect.
• Following are the main gases in the Earth's
atmosphere that cause the greenhouse effect:
• (1) Water vapor, (2) Carbon dioxide, (3)
Methane, (4) Nitrous oxide
29. THE GREEN HOUSE EFFECT
• Although the Earth's atmosphere naturally
contains these greenhouse gases, over the past
few decades their presence has increased,
causing the temperature of the earth to increase.
30. THE GREEN HOUSE EFFECT
• The following human activities are the biggest
contributors to the increase of greenhouse gases:
(1) Burning gasoline to drive cars and trucks.
(2) Burning oil, coal or wood to produce electricity
for heating, cooling and other purposes.
(3) Burning forests to clear land.
31. THE GREEN HOUSE EFFECT
Experiment:
• Take two jars and put a teaspoon of water in
each jar. Put a lid on just one jar. Place both
jars in a sunny spot. After a few hours, check
on the jars. You'll see that the open jar hasn't
changed, but the closed jar will be steamy
and hot inside. What happened? The heat
from the sun could not escape from the
closed jar, just like it can not escape from the
Earth's surface.
32. GLOBAL ENERGY BALANCE
• It is the global radiation balance at the top of
the atmosphere and at the earth's surface.
• Part of the total incoming solar energy 340
Watts/ m2 is absorbed by clouds and
atmospheric gases and part is reflected by
clouds, atmospheric gases and the ground
(land and water surfaces).
33. GLOBAL ENERGY BALANCE
• Approximately half (170 Watts/ m2) is
absorbed by the ground. Some of this energy
is re-radiated upward and some transferred to
the atmosphere as ‘sensible’ and ‘latent’ heat
by turbulence and convection.
• The atmosphere radiates infrared radiation in
all directions.
34. GLOBAL ENERGY BALANCE
• When balance is achieved in the atmosphere,
the total (short wave and long wave) upward
radiation from the top of the atmosphere
equals the 340 Watts/ m2 received from the
sun.
36. RADIATIVE FORCING OF CLIMATE
CHANGE
• Radiative forcing is generally defined as the
change in net irradiance between different
layers of the atmosphere. (irradiance is the
density of radiation incident on a given
surface usually expressed in watts per square
centimeter or square meter).
• Typically, radiative forcing is quantified at the
troposphere in units of watts per square
meter.
37. RADIATIVE FORCING OF CLIMATE
CHANGE
• A positive forcing (more incoming energy)
tends to warm the system, while a negative
forcing (more outgoing energy) tends to cool
it.
• Sources of radiative forcing include changes in
insolation (incident solar radiation) and in
concentrations of radiatively active gases and
aerosols.
38. CARBON DIOXIDE (CO2)
• CO2 Concentrations are now almost 30%
higher than they were just before the
industrial revolution.
• Carbon Dioxide (CO2) is a colorless, odorless
non-flammable gas and is the most prominent
Greenhouse gas in Earth's atmosphere.
39. CARBON DIOXIDE (CO2)
• It is recycled through the atmosphere by the
process photosynthesis, which makes human
life possible. Photosynthesis is the process of
green plants and other organisms
transforming light energy into chemical
energy.
• Light Energy is trapped and used to convert
carbon dioxide, water, and other minerals into
oxygen and energy rich organic compounds.
40. CARBON DIOXIDE (CO2)
• Carbon Dioxide is emitted into the air as
humans exhale, burn fossil fuels for energy,
and deforests the planet.
• Every year humans add over 30 billion tons of
carbon dioxide in the atmosphere by these
processes, and it is up thirty percent since
1750.
41. CARBON DIOXIDE (CO2)
• An isolated test at Mauna Loa in Hawaii
revealed more than a 12% (316 ppm in 1959
to 360 ppm in 1996) increase in mean annual
concentration of carbon dioxide.
• Mauna Loa, located in Hawaii, is the world’s
largest volcano at 40,000 cubic km and 4,170
meters above sea level.
42. METHANE (CH4)
• CH4 Concentrations are now increasing as a
result of human activities.
• Methane is a colorless, odorless, flammable
gas.
• It is formed when plants decay and where
there is very little air.
• It is often called swamp gas because it is
abundant around water and swamps.
43. METHANE (CH4)
• Bacteria that breakdown organic matter in
wetlands and bacteria that are found in cows,
sheep, goats, buffalo, termites, and camels
produce methane naturally.
• Since 1750, methane has doubled, and could
double again by 2050. Each year we add 350-500
million tons of methane to the air by raising
livestock, coal mining, drilling for oil and natural
gas, rice cultivation, and garbage sitting in
landfills.
• It stays in the atmosphere for only 10 years, but
traps 20 times more heat than carbon dioxide.
45. NITROUS OXIDE (N20):
(LAUGHING GAS)
• (N20) Concentrations are now increasing as a
result of human activities.
• It is released into the atmosphere mostly
during the nitrification portion of the nitrogen
cycle.; NH+
4 → N2 →N2O → NO–
2 → NO–
3
• Natural sources are oceans and wet forest
soils.
• Anthropogenic emissions are the result of
tropical agriculture.
46. NITROUS OXIDE (N20):
(LAUGHING GAS)
• Other sources include combustion of fuels
containing nitrogen, and a variety of industrial
processes such as the production of nylon.
• Nitrous oxide is another colorless greenhouse
gas; however, it has a sweet odor. It is
primarily used as an anesthetic because it
deadens pain and for this characteristic is
called laughing gas.
• This gas is released naturally from oceans and
by bacteria in soils.
47. NITROUS OXIDE (N20):
(LAUGHING GAS)
• Nitrous oxide gas raised by more than 15%
since 1750.
• Each year we add 7-13 million tons into the
atmosphere by using nitrogen based fertilizers,
disposing of human and animal waste in
sewage treatment plants, automobile exhaust,
and other sources not yet identified.
• It is important to reduce emissions because the
nitrous oxide we release today will still be
trapped in the atmosphere 100 years from now.
48. HALOCARBONS
• Halocarbons are carbon based molecules that
have chlorine, fluorine, or bromine in them.
• They contribute global warming as well as
they have ability to destroy ozone.
• Some greenhouse gases, such as industrial
halocarbons, are only made by humans, and
thus their presence in the atmosphere can
only be explained by human activity.
49. HALOCARBONS
• The most commonly occurring halocarbon is
methyl chloride (CH3Cl), which is produced
variously through fungal decaying, marine
organism metabolism and burning of biomass
(e.g. forest fires).
• Other sources of halocarbons are as follows:
(a) Release of refrigerants into the
atmosphere.
50. HALOCARBONS
(b) Accidental release of tetrachloroethylene,
carbon tetrachloride and other industrial
solvents into the environment.
(c) Slash-and burn agriculture, whereby
indigenous people burn forests for quick yields
of charcoal and first year crops.
51. HALOCARBONS
• Since most halocarbons absorb radiant reflected
sunlight, they contribute to the heating of the
troposphere, and thus function as a greenhouse
gas.
• Although there is a wide variation in the Global
Warming Potential (GWP) among the
halocarbons, these chemicals generally have a
much greater GWP than either methane or
carbon dioxide.
• Halocarbons which reach the stratosphere have
significant effects of destroying the ozone layer.
52. OZONE GAS: (O3)
• The ozone layer is a belt of naturally occurring
ozone gas that sits 9.3 to 18.6 miles (15 to 30
kilometers) above Earth and serves as a shield
from the harmful ultraviolet B-radiation
emitted by the sun.
54. OZONE GAS: (O3)
• Ozone is a highly reactive molecule that
contains three oxygen atoms. It is constantly
being formed and broken down in the high
atmosphere, 6.2 to 31 miles (10 to 50
kilometers) above Earth, in the region called
the stratosphere.
55. OZONE GAS: (O3)
• Today, there is widespread concern that the
ozone layer is deteriorating due to the release
of pollution containing the chemicals chlorine
and bromine. Such deterioration allows large
amounts of ultraviolet B rays to reach Earth,
which can cause skin cancer and cataracts in
humans and harm animals as well.
56. OZONE GAS: (O3)
• Chlorofluorocarbons (CFCs), chemicals found
mainly in spray aerosols heavily used by
industrialized nations for much of the past 50
years, are the primary culprits in ozone layer
breakdown. When CFCs reach the upper
atmosphere, they are exposed to ultraviolet
rays, which cause them to break down into
substances that include chlorine. The chlorine
reacts with the oxygen atoms in ozone and
rips apart the ozone molecule.
57. OZONE GAS: (O3)
• According to the U.S. Environmental
Protection Agency, one atom of chlorine can
destroy more than a hundred thousand ozone
molecules.
60. AEROSOLS
• Suspensions of particles having an effective
diameter of less than 10µm are called
aerosols.
• Some particles enter the atmosphere as solids
(e.g. solid dust) and other are formed in the
atmosphere when gases such as sulfur dioxide
condense into liquid particles such as sulfates.
• Combustion of fossil fuels and biomass
burning are the principal sources.
61. AEROSOLS
• They affect the earth’s energy balance in
following three ways.
(1) They can reflect incoming solar radiation back
into space, which increase the earth’s albedo.
(2) They can provide cloud the condensation
nuclei, which increases the clouds reflectivity and
cloud lifetime, and those also increases albedo.
(3) Carbonaceous particles, such as soot from
fossil-fuel combustion, can increase the
atmosphere absorption of incoming solar energy.
62. AEROSOLS
• CO2, Nitrous oxide (N2O), Methane (CH4), and
halocarbons are well mixed, long-lived
greenhouse gases. Lifetime of these gases is
measured in decades. Lifetime of Aerosols is
measured in days.
• When you look up at the sky, you are looking at
more than just air. There are also billions of tiny
bits of solid and liquid floating in the
atmosphere. Those tiny floating particles are
called aerosols or particulates.
63. AEROSOLS
• Some aerosols are so small that they are made
only of a few molecules – so small that they are
invisible because they are smaller than the
wavelength of light. Larger aerosols are still very
small, but they are visible.
• There are hundreds or thousands of little
aerosols in each cubic centimeter of air. Some of
them are natural and others are released into the
air by humans.
64. AEROSOLS
• Natural sources of aerosols include dust from dry
regions that is blown by the wind, particles
released by erupting volcanoes or forest fires,
and salt from the ocean.
• We, humans, add aerosols to the atmosphere
too. Aerosols are a part of air pollution from cars,
power plants, and factories that burn fossil fuels.
65. AEROSOLS
• Some aerosols are released into the atmosphere,
others are made in the atmosphere. For
example, sulfate aerosols are made in the
atmosphere from sulfur dioxide released from
power plants.
67. AEROSOLS
• In general, the smaller and lighter a particle is,
the longer it will stay in the air. Larger particles
tend to settle to the ground by gravity in a
matter of hours whereas the smallest particles
(less than 1 micrometer) can stay in the
atmosphere for weeks and are mostly removed
by precipitation.
68. AEROSOLS
• For several reasons, aerosols affect climate.
• Aerosols help clouds to form in the sky and the
number and types of clouds affects climate.
• Certain types are able to scatter or absorb
sunlight, which affects climate.
• Aerosols that scatter light can make interesting
distortions in the sky, called atmospheric optics.
69. AEROSOLS
• The aerosols that are from air pollution are
hazardous to human health.
• When the little particles get deep into a person’s
lungs it can make him or her very ill.
• Aerosols can also limit visibility, causing haze in
many parts of the world.
70. GLOBAL WARMING POTENTIAL
• CH4 (Methane) has a global warming potential
of 21 because it is 21 times as powerful as a
greenhouse gas as CO2 (CO2 has a GWP of 1).
• Global-warming potential (GWP) is a relative
measure of how much heat a greenhouse gas
traps in the atmosphere.
• It compares the amount of heat trapped by a
certain mass of a gas to the amount of heat
trapped by a similar mass of CO2.
72. THE CARBON CYCLE
• Carbon is an element. It is part of oceans, air,
rocks, soil and all things. Carbon doesn’t stay in
one place. It is always on the move.
• Carbon moves from the atmosphere to plants: In
the atmosphere, carbon is attached to oxygen in
a gas called (CO2). With the help of the Sun,
through the process of photosynthesis, carbon
dioxide is pulled from the air to make plant food
from carbon.
73. THE CARBON CYCLE
• Carbon moves from plants to animals.
Through food chains, the carbon that is in
plants moves to the animals which eat them.
Animals that eat other animals get the carbon
from their food too.
74. THE CARBON CYCLE
• Carbon moves from plants and animals to the
ground.
When plants and animals die, their bodies,
wood and leaves decay bringing the carbon
into the ground. Some becomes buried miles
underground and will become fossil fuels in
millions and millions of years.
75. THE CARBON CYCLE
• Carbon moves from living things to the
atmosphere.
Each time you exhale, you are releasing
carbon dioxide gas (CO2) into the atmosphere.
Animals and plants get rid of carbon dioxide
gas through a process called respiration.
76. THE CARBON CYCLE
• Carbon moves from fossil fuels to the atmosphere
when fuels are burned.
When humans burn fossil fuels to power factories,
power plants, cars and trucks, most of the carbon
quickly enters the atmosphere as carbon dioxide
gas. Each year, five and a half billion tons of carbon
is released by burning fossil fuels. That’s the weight
of 100 million adult African elephants! Of the huge
amount of carbon that is released from fuels, 3.3
billion tons enters the atmosphere and most of the
rest becomes dissolved in seawater.
77. THE CARBON CYCLE
• Carbon moves from the atmosphere to the
oceans.
The oceans, and other bodies of water, soak
up some carbon from the atmosphere.
78. THE CARBON CYCLE
• Carbon dioxide is a greenhouse gas and traps
heat in the atmosphere. Without it and other
greenhouse gases, Earth would be a frozen
world. But humans have burned so much fuel
that there is about 30% more carbon dioxide
in the air today than there was about 150
years ago.
• Most of the carbon in the atmosphere exists
as carbon dioxide (CO2) and to a lesser extent,
methane (CH4).
79. THE CARBON CYCLE
• Although CO2 and CH4 are trace gases, which
occur in very small concentrations, they are
both important greenhouse gases.
• The concentration of CO2 and CH4 in the
atmosphere strongly affects the strength of
the greenhouse effect and consequently the
Earth's mean temperature.
81. CARBON EMISSIONS FROM FOSSIL
FUELS
• Fossil fuel usage is expected to increase as the
world's population continues to increase.
• Scientists have determined that approximately
40% of the carbon dioxide produced by
burning fossil fuels is being absorbed by the
terrestrial and ocean biosphere.
• The other 60% is staying in the atmosphere,
and as a consequence, carbon dioxide is at its
highest level in millions of years.
82. CARBON EMISSIONS FROM FOSSIL
FUELS
• So, what can individuals, organizations or
governments do to reduce the amount of CO2
in the atmosphere?
• The burning of fossil fuels pollutes the
atmosphere, degrades local environments,
causes health and smog problems.
84. THE OCEANS AND CLIMATE CHANGE
• The ocean has been called the "global heat
engine." Energy escapes the ocean in the forms
of heat and water vapor.
• As the atmosphere warms, temperature gradients
are created, resulting in surface winds that, in
turn, drive ocean currents.
• These winds and water vapor also dramatically
affect meteorological conditions, resulting in the
formation of clouds or even rainstorms that are
vital for life on land.
86. THE OCEANS AND CLIMATE CHANGE
• Sea spray and water vapor form low clouds that
ultimately cool temperatures at the surface.
• Meanwhile, desert dust and carbon dioxide settle
into the ocean and act as "fertilizer" to stimulate
the growth of phytoplankton (plankton consisting
of microscopic plants), thereby enhancing the
ocean's ability to absorb carbon dioxide from the
atmosphere -- a process known as the "biological
pump."
89. THE OCEANS AND CLIMATE CHANGE
• Phytoplankton forms the basis of the marine
food chain.
• “Phytoplankton is the fuel on which marine
ecosystems run. A decline of phytoplankton
affects everything up the food chain, including
humans.”
91. CHANGES IN STRATOSPHERIC OZONE
• By the time chlorine-containing compounds
reach the stratosphere, they have been
distributed globally. However, ozone depletion is
most significant at the poles and in particular
over the Antarctic continent at the South Pole.
• Figure indicates the large difference between
ozone concentrations at the South and North
Poles.
• Change in stratospheric ozone concentrations in
the stratosphere is shown in the figure below.
