Transcript ATMOSPHERE - Los Angeles Mission College

ATMOSPHERE
GASES, LAYERS,
TEMPERATURES
7/21/2015
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EARTH’S ATMOSPHERE FROM
SPACE
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COMPONENTS OF THE GLOBAL
CLIMATE SYSTEM
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WHAT IS THE ATMOSPHERE?
 The atmosphere is a gaseous realm
 Humans live at the bottom of an ‘ocean of
air’
 Atmospheric conditions can exert an
influence on the Earth’s surface
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ORIGIN OF EARTH’S
ATMOSPHERE
 Original atmosphere developed approximately 4.6 billion
years ago
– Two main gases: Helium and Hydrogen
 By products of Sun’s ‘nuclear’ fusion reaction
– Water vapor (H2O) and Nitrogen (N) introduced later
 Water Vapor sources
– Outgassing from volcanoes introduced water vapor (H2O)
 Water trapped in mantle rocks percolated to the surface
 Condensation and precipitation formed world’s ocean
- Other possible water source: Comets and Meteors
 Nitrogen introduced soon after Helium and Hydrogen
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CONTEMPORARY ATMOSPHERE

Contemporary atmosphere developed approximately 3.5-2.4 Billion
years ago with introduction of a toxic, corrosive and explosive
(‘combustible’) gas:
– OXYGEN (O2)!!
 Released by photo-dissociation of H2O
 Produced by Blue-green algae (Stromatolites)
 Oxygen constituted a wholesale pollution of the environment;
a "holocaust" for all living things on Earth.
 Oxygen needed for ozone shield protecting Earth surface from
damaging ultra-violet rays
– Ozone shielding allowed ‘life’ to move into shallow water and eventually
onto land.
 Oxygen build-up allowed the appearance of the first
eukaryotic cells (PLANTS, FUNGI, AND ANIMALS)
 Eukaryotic cells require oxygen for their more complicated and more
efficient metabolism.
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COMPOSITION OF ATMOSPHERE
 Permanent Gases
– Nitrogen – 78% by volume
– Oxygen – 21% by volume
– Remaining gases - <1% by volume
 Argon
 Neon
 Helium
 Hydrogen
 Xenon
 Krypton
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COMPOSITION OF ATMOSPHERE
 Variable Gases (Also Greenhouse Gases)
–
–
–
–
–
–
Water Vapor – 0-4% by volume
Carbon Dioxide (CO2) – 0.035% (350 parts per million)
Methane (CH4) - 0.00017% (0.17 ppm)
Nitrous Oxide (N2O) – 0.00003% (0.03 ppm)
Ozone (O3) – 0.000004% (0.004 ppm)
Chlorofluorocarbons (CFCs) – 0.00000001% (0.00001 ppm)
 Particulates – airborne solids and aerosols
– Windblown dust
– Salt crystals from oceans
– Aerosols
 Solid or liquid particles less than 100 microns diameter
– Volcanic Ash
– Condensation aerosols
 Formed by condensations of vapor or reactions of gases
– Smoke/Soot
 Forest fires
 Industries
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GREENHOUSE EFFECT
 Energy from the sun (short-wave energy) heats the Earth’s
surface
 The Earth radiates long-wave “infrared” energy back into
space.
 Absorption of Earth’s long-wave radiation by some
atmospheric gases add additional heat energy to the
atmospheric system.
 Warmer atmospheric greenhouse gas molecules radiate longwave energy in all directions.
 Over 90 % of this emission of long-wave energy is directed
back to the Earth's surface, where it once again is
absorbed by the surface
 Without “greenhouse effect,” the heat would escape to
outer space
– Average temperature of the Earth would drop from an
average of +15 degrees Celsius to -18 degrees
Celsius!
– Life as we know it could not survive
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GREENHOUSE EFFECT
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GREENHOUSE GASES – CARBON
DIOXIDE (CO2)
 CARBON DIOXIDE (CO2)
 A colorless, odorless gas, denser than air
– Absorbed and stored in vegetation during photosynthesis
– Stored in world’s oceans by phytoplanktons
 Carbonate
– Main component of chalk, shells, coral reefs, limestone
– Released:
 Respiration – animal life (all forms)
 Volcanic eruptions
 Deforestation – 35% of global CO2
– Conversion of forested lands, prairies and woodland into agricultural lands
– Natural release due to decay of dead vegetation
 Burning of fossil fuels – 65% of global CO2
– Oil, Natural Gas, Coal
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RESPIRATION
 Respiration is a key component
of the global carbon cycle.
– Plant respiration
– Animal respiration
 However, the direct contribution
to atmospheric carbon dioxide
concentrations via respiration is
relatively insignificant
 Of more concern is the impact
human-induced global warming
could have on global respiration
rates.
 Increasing temperatures means
rates of respiration may also
increase in many organisms.
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Volcanic Eruptions – CO2 Emissions
 CO2 is the second most
abundant gas released
during volcanic eruptions
 Concentrated CO2
emissions kill vegetation,
animals and even humans
near volcanic openings
 Volcanoes emit between
about 145-255 million tons
of CO2 into the
atmosphere every year
– Emissions by human
activities contribute about 24
billion tons every year
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DEFORESTATION – CO2
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DEFORESTATION – CAUSES AND
CONSEQUENCES
 Deforestation due to:
– Logging
 timber or pulp
– Agricultural purposes
 Cultivation:
– Slash-Burn
agriculture
 Cattle grazing
– World demand for
beef
 Consequences:
– Increased carbon dioxide
(CO2) and other trace gases
in the atmosphere
– 460-575 billion
metric tons of carbon
stored in tropical
forests worldwide
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FOSSIL FUEL CONSUMPTION
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CO2 FOSSIL FUEL SOURCES
 Emissions per ton of oil
equivalent or “toe” (1 toe =
11600 kWh = the energy
freed by the combustion of
one ton of oil )
U.S. CO2 Emissions vs. World
California Fossil Fuel CO2
Emission Sources
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FOSSIL FUEL CONSEQUENCES
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FOSSIL FUEL CONSEQUENCES
 CO2 is used as a common denominator, and
values of other gases are expressed in CO2
equivalents
 CO2 may contribute to global warming
 Future carbon dioxide levels are expected to
continue rising due to ongoing fossil fuel
usage
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METHANE (CH4)
 CH4 is released in the decay process of
organic material
 Most common sources:
– Wetlands
– Bacteria in rice paddies
 Wet anaerobic soils
– Biochemical reactions in stomach of ruminants
and termites
– Landfills
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TABLE OF METHANE SOURCES –
TgCH4
Source Category
1990
1997
1998
1999
2000
2001
2002
2003
Landfills
172.2
147.4
138.5
134
130.7
126.2
126.8
131.2
Natural Gas Systems
128.3
133.6
131.8
127.4
132.1
131.8
130.6
125.9
Enteric Fermentation
117.9
118.3
116.7
116.8
115.6
114.5
114.6
115
Coal Mining
81.9
62.6
62.8
58.9
56.2
55.6
52.4
53.8
Manure Management
31.2
36.4
38.8
38.8
38.1
38.9
39.3
39.1
Wastewater Treatment
24.8
31.7
32.6
33.6
34.3
34.7
35.8
36.8
Petroleum Systems
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18.8
18.5
17.8
17.6
17.4
17.1
17.1
Rice Cultivation
7.1
7.5
7.9
8.3
7.5
7.6
6.8
6.9
Stationary Sources
7.8
7.4
6.9
7.1
7.3
6.7
6.4
6.7
Abandoned Coal Mines
6.1
8.1
7.2
7.3
7.7
6.9
6.4
6.4
Mobile Sources
4.8
4
3.9
3.6
3.4
3.1
2.9
2.7
Petrochemical Production
1.2
1.6
1.7
1.7
1.7
1.4
1.5
1.5
Iron and Steel
1.3
1.3
1.2
1.2
1.2
1.1
1
1
Agricultural Residue Burning
0.7
0.8
0.8
0.8
0.8
0.8
0.7
0.8
605.3
579.5
569.3
557.3
554.2
546.7
542.3
544.9
Total for U.S.
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METHANE - WETLANDS
 The largest sources of
methane are the
wetlands of the world
 One-fifth of all
methane is emitted by
wetlands
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RICE PADDIES
 More than 60 % of all rice
paddies are found in India and
China where scientific data
concerning emission rates are
unavailable.
 Contribution of rice paddies is
large because this form of crop
production has more than
doubled since 1950.
– At between 50 and 100 million
tons of methane a year, rice
agriculture is a big source of
atmospheric methane
 (possibly the biggest of manmade methane sources)
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BIOCHEMICAL SOURCES OF
METHANE
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METHANE and LIVESTOCK
 Methane emission from ruminant livestock is
currently estimated to be around 100 million
tons each year
 Methane is produced in the guts of ruminant
livestock as a result of methanogenic
bacteria and protozoa.
– After rice agriculture, represents the biggest
man-made methane source
– Sheep can produce about 30 liters of methane
each day and a dairy cow up to about 200.
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METHANE AND TERMITES
 Global emissions of termites
account for approximately 11%
of the global methane emissions
from natural sources.
 Methane is produced in termites
as part of their normal digestive
process, and the amount
generated varies among
different species.
–
Termites produce methane in their gut as
they digest woody plant material
 Ultimately, emissions from
termites depend largely on the
population of these insects,
which can also vary significantly
among different regions of the
world.
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METHANE AND LANDFILLS
 In a landfill, biogenic waste is
consumed by aerobic bacteria
 After oxygen is depleted,
anaerobic bacteria take over
 Through fermentation
processes, methane is produced
 Methane must be released
carefully – it is an explosive gas
– A grid system of perforated
pipes connected to vacuum
blowers collect and remove the
gas.
– The landfill gas is either burned
off in a flare, or used to
generate electricity in a gas
turbine
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NITROUS OXIDE (N2O)
 N2O forms in the soil as a result of bacteria and microbes
interactions
 Sources include land-use conversion; fossil fuel
combustion; biomass burning; and soil fertilization
 PRIMARY SOURCE: deforestation and the conversion of
forest, savanna and grassland ecosystems into agricultural
fields and rangeland
– The use of nitrate and ammonium fertilizers to enhance plant
growth is another source of nitrous oxide.
 SECONDARY SOURCE: the presence or absence of
control devices on combustion sources, such as catalytic
converters on automobiles, can have a significant effect on
the level of N2O emissions.
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NITROUS OXIDE TABLE – TgN2O
Source Category
1990
1997
1998
1999
2000
2001
2002
2003
Agricultural Soil Management
253
252
267.7
243.4
263.9
257.1
252.6
253.5
Mobile Sources
43.7
55.2
55.3
54.6
53.2
49
45.6
42.1
Manure Management
16.3
17.3
17.4
17.4
17.8
18
17.9
17.5
13
14.7
15
15.4
15.6
15.6
15.7
15.9
Nitric Acid
17.8
21.2
20.9
20.1
19.6
15.9
17.2
15.8
Stationary Sources
12.3
13.5
13.4
13.5
14
13.5
13.5
13.8
5.5
6.1
6.1
6.2
6
5.8
6
6
15.2
10.3
6
5.5
6
4.9
5.9
6
N2O Product Usage
4.3
4.8
4.8
4.8
4.8
4.8
4.8
4.8
Waste Combustion
0.4
0.4
0.3
0.3
0.4
0.4
0.5
0.5
Agricultural Residue Burning
0.4
0.4
0.5
0.4
0.5
0.5
0.4
0.4
Remaining Forest Land
0.1
0.3
0.4
0.5
0.4
0.4
0.4
0.4
Total for U.S.
382
396.2
407.8
382.1
402.2
385.9
380.5
376.7
Human Sewage
Remaining Settlements
Adipic Acid
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NITROUS OXIDE SOURCES
Natural sources: 10 million tons/yr
Man-made sources: 8 million
tons/yr
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NITROUS OXIDE (N2O CYCLE)
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NITROUS OXIDE – CATALYTIC
CONVERTER
 Nitrous oxide comprises
7.2% of global warming
gases.
 Cars and trucks, most
fitted with catalytic
converters, produce nearly
half of that gas
 Nitrous oxide is produced
during the reaction of
nitrogen oxide (NO) and
ammonia (NH3) over the
platinum in the catalytic
converter
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OZONE – O3
 Ozone is formed naturally by chemical
combination of O2 and O in the presence of
sunlight
 Ozone is a form of Photochemical pollution in
lower atmosphere
 Ozone forms a protective layer in upper
atmosphere
– Maximum Ozone concentration found approximately 30
kilometers above surface of Earth
– The ozone layer in the acts like a giant sunshade,
protecting plants and animals from much of the sun's
harmful ultraviolet radiation.
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OZONE IN ATMOSPHERE
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DECLINE IN STRATOSPHERIC
OZONE
 Global stratospheric ozone levels have declined
– Significant evidence of a thinning of the ozone layer during spring
and summer
 Chlorofluorocarbons (CFCs), halons, methyl chloroform,
methyl bromide, carbontetrachloride and several other
chemicals are ozone-depleting substances
– When CFCs and halons are released into the atmosphere, they rise
slowly, taking up to seven years to reach the stratosphere.
– Under the influence of the sun's ultraviolet light, chlorine is released
and reacts with ozone, with a depletion of the ozone layer as a
consequence.
 This allows harmful solar UV radiation to pass through to the earth's
surface
 Some of the ozone depleting substances are persistent, remaining
active in the atmosphere for up to 50 years.
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OZONE AND CFCS
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CHLOROFLUOROCARBONS
(CFCS)
 CFCs are man-made compounds created for the
following purposes:
– Propellants
 Hair spray, deodorant, spray paint
– Refrigeration
 Freon in refrigerators, freezers, air conditioners
– Solvents
 Cleaning materials – especially dry cleaners
– Insulation
– Exhaust from some aircraft
 SSTs ‘Concorde’
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HOLE IN OZONE LAYER

An ozone "hole" is what scientists
call an "ozone depletion area" in
that region of Earth's atmosphere
– The depletion area usually appears
with the southern hemisphere
spring (August - October)




The 2003 ozone hole covered 11.1
million square miles, making it the
second largest ever recorded
The 2005 hole covered about 10
million square miles
While the ozone hole may appear
for as much as 40 more years, it is
expected to improve
Consequences: UV radiation
exposure
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OZONE HOLE: ANTARCTICA 2009
Ozone hole covering 9.2 million
square miles (September 2009)
Measuring Dobson Units (DU): amount of ozone in a vertical column of air
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PARTICULATES
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PARTICULATES SOURCES
 Particulates introduced directly into the air
can originate from natural fires, volcanic
eruptions, the ejection of salt crystals by
breaking ocean waves
– and as any sufferer of hay fever can tell you, by
the entrainment of pollen by wind.
 Human activities, especially those involving
combustion, produce primary and secondary
particulates.
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HEALTH ISSUES
 Fine particulates are so small
that they can easily be inhaled
into the deepest reaches of our
lungs, causing serious lung and
heart disease.
Electronmicrograph of
flyash: trash incineration
– Fine particulates are linked with
all sorts of health problems —
from a runny nose and
coughing, to bronchitis,
emphysema, asthma and even
death.
 Fine particulates are also a
visual blight, capable of
reducing visibility so much that
beautiful views are blotted out
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ATMOSPHERE LAYERS
 Troposphere: 0-11 km
– Tropopause
 Stratosphere: 18-50 km
– Stratopause
 Mesosphere: 55-90 km
– Mesopause
 Thermosphere: 95 km200km?
 Exosphere: up to 500
km?
 Ionosphere
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LOWER ATMOSPHERE TROPOSPHERE
 The lowest layer of the atmosphere
– All weather occurs here: clouds, winds, storms, etc
 Extends to an average of 11 kilometers above the
surface
– Higher elevation near equator
– Lower elevation near poles
 Temperature decreases at a consistent rate in the
troposphere
 Tropopause – upper boundary of troposphere
– No temperature change in this boundary
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UPPER ATMOSPHERE
 STRATOSPHERE – the beginning of the upper
atmosphere at approximately 20 kilometers above
surface
– Extends to 50 kilometers
 Ozone layer – concentration at 30 kilometers
above surface
 Temperature increases in this layer as UV
radiation is absorbed by ozone
 Stratopause is the uppermost boundary
– No temperature change in this boundary
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UPPER ATMOSPHERE
 MESOSPHERE – begins at approximately
55 kilometers above surface
– Extends to approximately 90 kilometers
 Atmosphere very thin, temperatures
decrease with elevation
 Mesopause is uppermost boundary
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UPPER ATMOSPHERE
 THERMOSPHERE – beginning at 95
kilometers above surface
 Temperature increases due to molecular
Oxygen absorbing solar radiation
 Exosphere – the final boundary between
Earth’s atmosphere and outer space
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IONOSPHERE
 Not a true layer of atmosphere – extends throughout much
of upper atmosphere
 An electrified region consisting of IONS
– Ions are atoms that have lost or gained electrons
 The visible manifestation of the high-energy ions is seen in
the auroras, the colorful Northern and Southern Lights that
appear at 90 to 160 kilometers above Earth
– The light is emitted when charged particles from the sun are guided
by the earth's magnetic field into the atmosphere near the poles.
– When the particles contact atmospheric molecules, primarily
oxygen and nitrogen, at altitudes from 300 km down to 100 km, a
part of the energy of the collisions transforms to visible light.
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AURORA BOREALIS AND AURORA
AUSTRALIS
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MAGNETOSPHERE AND AURORAS

The sun spews out charged
particles traveling at a million miles
per hour known as the solar wind.
– Charged particles, mostly protons
and electrons, emitted from the
outer region of the Sun (corona)
reach the magnetosphere of Earth
having a velocity of some 350 to
400 kilometers per second.

Particles which stream out of
sunspots may be captured by the
Earth's magnetic field and create
the aurora.
– Electrons and protons collide with
the gas particles in the outer
atmosphere
– The excited electrons return to their
‘normal’ states by emitting light of
distinct wavelength and thus a
distinct color
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