Air Resources and State of the Atmospheric Environment

8/14/2019 Air Resources and State of the Atmospheric Environment

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Air Resources and State of the

Atmospheric Environment


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The Earths Atmosphere

Blanket of air surrounding the earth that protects

us by blocking the dangerous radiation from the

sun and reducing temperature extremes betweenday and night.

Composed of mixture of gases that gradually thins

out as it reaches space

composed of Nitrogen (78%), Oxygen (21%), and

other gases (1%).


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Composition of the Atmosphere

Percent Composition ofDry Atmosphere,by volume - ppmv: partsper million by volume

Gasper NASA

Nitrogen (N2)

78.084%

Oxygen (O2)

20.946%

Argon (Ar)

0.9340%
http://en.wikipedia.org/wiki/Parts_per_millionhttp://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.htmlhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Image:Atmosphere_gas_proportions.gifhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Nitrogenhttp://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.htmlhttp://en.wikipedia.org/wiki/Parts_per_million


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Carbon dioxide (CO2)

365 ppmv

Neon (Ne) 18.18 ppmv Helium (He) 5.24 ppmv

Methane (CH4)1.745 ppmv

Krypton (Kr) 1.14 ppmv

Hydrogen (H2) 0.55 ppmv

Not included in above

composition

of dry atmosphere:

Water vaporHighly variable;

typically makes up about 1%

Minor components of airnot listed above include:

nitrous oxide (0.5 ppmv

xenon (0.09 ppmv) ozone (0.0 to 0.07 ppmv,

0.0 to 0.02 ppmv inwinter)

nitrogen dioxide (0.02

ppmv), iodine (0.01 ppmv),

carbon monoxide (0.0 totrace)

ammonia (0.0 to trace).
http://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Heliumhttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Kryptonhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Nitrous_oxidehttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Ozonehttp://en.wikipedia.org/wiki/Winterhttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Carbon_monoxidehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Nitrogen_dioxidehttp://en.wikipedia.org/wiki/Winterhttp://en.wikipedia.org/wiki/Ozonehttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Nitrous_oxidehttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Kryptonhttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Heliumhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Carbon_dioxide


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The evolution of the Earth's

atmosphere The modern atmosphere is sometimes

referred to as Earth's "third atmosphere", in

order to distinguish the current chemicalcomposition from two notably differentprevious compositions.

The original atmosphere was primarilyhelium and hydrogen; heat (from the stillmolten crust, and the sun) dissipated thisatmosphere.


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About 3.5 billion years ago, the surface had cooled

enough to form a crust, still heavily populated

with volcanoes which released steam,carbon dioxide, and ammonia.

This led to the "second atmosphere"; which was,

primarily, carbon dioxide and water vapor, with

some nitrogen but virtually no oxygen

This second atmosphere had ~100 times as much

gas as the current atmosphere. It is generally

believed that the greenhouse effect, caused byhigh levels of carbon dioxide, kept the Earth from

freezing.
http://en.wikipedia.org/wiki/Crusthttp://en.wikipedia.org/wiki/Volcanohttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Multiplicationhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Freezinghttp://en.wikipedia.org/wiki/Freezinghttp://en.wikipedia.org/wiki/Greenhouse_effecthttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Multiplicationhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Water_vaporhttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Volcanohttp://en.wikipedia.org/wiki/Crust


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In the next few billion years, water vapor condensed to

form rain and oceans, which then dissolved the carbon

dioxide

About 50 % of CO2 were absorbed into the ocean

The first life forms were the cyanobacteria and were the

first oxygen producing evolving phototropic organisms.

Cyanobacteria converted the earths atmosphere froman anoxic (state without oxygen) to an oxic (with

oxygen) state. Being the first to carry out oxygenic

photosynthesis, they were able to convert carbon

dioxide into oxygen playing a major role inoxygenating the atmosphere.


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Eventually, photosynthesizing plants evolved andconverted more carbon dioxide to oxygen

Excess carbon were locked in fossil fuels,sedimentary rocks (limestone), and animal shells.

The oxygen released reacted with ammonia to formnitrogen, aside from bacteria converting ammonia to

nitrogen The appearance of more plants increased the levels

of oxygen significantly but the concentration of CO2dropped.

The oxygen produced first reacted with variouselements like iron but eventually accumulated in theatmosphere resulting to mass extinction and furtherevolution


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Ozone layer started

to appear and lifeforms were better

protected from the

UV

The oxygen-nitrogenatmosphere is the

"third atmosphere".
http://www.windows.ucar.edu/tour/link=/earth/images/atmosphere_image.html


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Air Resources

Nitrogen being the mostabundant gas in theatmosphere is formed from

reaction of ammonia withoxygen

Dilutes oxygen and carbondioxide

Helps slow down decay,

rusting, and burning Liquefaction and fractional

distillation of N2 from the

atmosphere

Uses of nitrogen

Cryogenics and refrigerant

responsible for the orange-red, blue-green, blue-violet,

and deep violet colors of theaurora.

Component of proteins,foods, fertilizers, poison, andexplosives

Annealing steel andblanketing medium duringproduction of electroniccomponents


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Oxygen is a by-

product of

photosynthesis

It combines easily

with many substances Supports life

Supports burning

process

Uses:

oxy-acetylene welding

frequently used to aidrespiration of patientsin hospitals

used in makingmethanol and ethene

oxide rocket fuel oxidant

steel manufacture

ozone (O3) in theatmosphere isprotection against thesun's ultraviolet rays


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Carbon dioxide although small in

concentration plays a role in warming theatmosphere

Produced by animal respiration, burning of

fuels, , and by volcanic eruption Important to life of plant

Not poisonous, but too much of it in the air

lessens the amount of oxygen breathed in byhumans and animals


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Carbon is one of the most common element that

has unique properties (can form bond with itself or

with other elements Found in all living organisms

Can be found in compounds that can exist as gas,

liquid, or solid on the earths surface Thus carbon can help form solid minerals such as

limestone, plants and animals, and carbon dioxide

that can be carried around the world through the

atmosphere and be dissolved in water This makes possible the existence of carbon in

compounds which are essential to life on earth


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Carbon atoms continually move through livingorganisms, the oceans, the atmosphere, and in thecrust of the planet (carbon cycle)

The paths taken by carbon through this cycle arecomplex and take millions of years to complete thecycle (coal and crude oil).

Others may take days or simply hours to pass the

cycle (Burning) The aggregation of the possible paths of carbon,

where it may be stored for extended periods (the"sinks"), where it is likely to be released to the

atmosphere (the "source"), and what triggers thosesources (the "release agents"), together defines thecarbon cycle.(Global Climates - Past, Present, and Future, S. Henderson, S. Holman, and L.Mortensen (Eds.). EPA Report No. EPA/600/R-93/126, U.S. Environmental Protection Agency, Office ofResearch and Development, Washington, DC. pp. 59 - 64.)


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The Carbon Cycle


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Carbon sinks includelong-lived trees,

limestone (formed fromthe carbon-containingshells of small seacreatures that settle tothe ocean bottoms and

build up into thickdeposits), plastic (amodern invention, butvery long-lived), and theburial of organic matter

(such as those thatformed the fossil fuelswe use today).


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Carbon sources

include the burning

of fossil fuels and

other organic matter,

the weathering of

limestone rocks(which releases ),

and the respiration

of living organisms.


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Release agents

include volcanic

activity, forest fires,and many human

activities.


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The other 1% is composed of "trace" gases, themost prevalent of which is the inert gaseouselement argon. The rest of the trace gases,although present in only minute amounts, arevery important to life on earth.

Two in particular, carbon dioxide and ozone, canhave a large impact on atmospheric processes.

Another gas, water vapor, also exists in smallamounts. It varies in concentration from beingalmost non-existent over desert regions to about4% over the oceans. Water vapor is important to

weather production since it exists in gaseous,liquid, and solid phases and absorbs radiantenergy from the earth.


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Other trace gases suchas methane, oxides of

nitrogen are transparentto UC radiation but canabsorb outgoinginfrared radiation, in

effect trapping the heatenergy. This trappedheat energy makes theearth warmer than itwould be without thesetrace gases. (GHG)


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This phenomenon has been called the"greenhouse effect" because the trace

gases trap heat similar to the way that agreenhouse's transparent coveringtraps heat.

Without our atmospheric greenhouseeffect, earth's surface temperaturewould be far below freezing.

On the other hand, an increase in

atmospheric trace gases could result inincreased trapped heat and risingglobal temperatures.


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It extends from the earth's

surface to an average of 12

km (7 miles).

The pressure ranges from

1000 to 200 millibars (29.92

in. to 5.92 in.).

The temperature generallydecreases with increasing

height up to the tropopause

(top of the troposphere);

this is near 200 millibars or36,000 ft.


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The temperature averages 15C (59F) near the

surface and -57C (-71F) at the tropopause.

The layer ends at the point where temperature no

longer varies with height. This area, known as the

tropopause, marks the transition to the

stratosphere.

Winds increase with height up to the jet stream. The moisture concentration decreases with height

up to the tropopause.

The air is much drier above the tropopause, in the

stratosphere.


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The sun's heat that warms the earth'ssurface is transported upwards largely by

convection and is mixed by updrafts and

downdrafts.

The troposphere is 70% and 21% . The

lower density of molecules higher up would

not give us enough to survive.


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Troposphere-air flow is

usually horizontal

Ozone layer responsiblefor absorbing the ultraviolet

radiation from the suin

Above the stratosphere is

the mesosphere and abovethat is the ionosphere (or

thermosphere), where

many atoms are ionized

(have gained or lost

electrons so they have a

net electrical charge).


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The ionosphere is very thin, but it is whereaurora take place, and is also responsible for

absorbing the most energetic photons fromthe Sun, and for reflecting radio waves,thereby making long-distance radiocommunication possible.

The structure of the ionosphere is stronglyinfluenced by the charged particle wind fromthe Sun (solar wind), which is in turngoverned by the level of Solar activity.


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State of the Atmospheric

Environment Most scientists believe that human

activity is altering the composition of the

atmosphere by increasing theconcentration of greenhouse gases

(GHGs). Greenhouse gases occur

naturally in the atmosphere and theirpresence results in what atmospheric

scientists call the greenhouse effect.


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It is important to remember that the

greenhouse effect is what keeps the earth

warm enough to be habitable.

The current concern is directed at an

enhanced greenhouse effect, one that

would put more heat-absorbing gases into

the atmosphere, thereby increasing globaltemperatures.

The enhanced greenhouse effect has

been linked to increased GHG emissionsfrom human activities.


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The recent attention given to the

greenhouse effect and global warming

is based on the recorded increases inconcentrations of some of the

greenhouse gases due to human

activity. Of particular interest are watervapor, carbon dioxide, methane, nitrous

oxide, chlorofluorocarbons, and ozone.

With the exception of

chlorofluorocarbons, all of these gases

occur naturally and are also produced

by human activity.


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Water vaporis the most important GHG on theplanet.

Unlike most of the other atmospheric gases, water

vapor is considered to be a 'variable' gas; that is,the percentage of water vapor in the atmospherecan vary greatly depending on the location andsource of the air.

Water vapor absorbs heat readily. human activity is not directly changing water vapor

content.

But man, directly influence other GHGs. Although

other GHGs are individually less important thanwater vapor, increasing their concentrations mayaffect global climate in significant and measurableways.


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Carbon dioxide (CO2) is considered the

most important human-influenced GHG.

Over geologic time, sources and sinks

generally balance. In today's

atmosphere, however, levels areclimbing in a dramatic and easily

measurable fashion, providing evidence

that there are now more sources thansinks.


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What are the sources for this

'extra' CO2? Human activities primarily responsible for the

increases Fossil fuel combustion accounts for 65%

Deforestation ( released from trees that are cutand burned or left to decay) accounts for 33%

The by-products of cement production account forthe remaining 2%


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natural sources of CO2 Plants and animals give off CO2 while alive

and respiring and when dead and decaying(bacteria that consume the dead bodiesrespire too, after all).

Carbonate rocks contain CO2 that can be

released by exposure to acid and/orweathering. Certain naturally carbonatedspring waters contain CO2 because the water

has passed though carbonate rocks on its wayto the surface.

Volcanoes geological sources are insignificant when

compared to the human sources.


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Methane (CH4 ) largely a product of natural biologic processes, but

its output can be accelerated by human activities.

emitted from the decay of organic matter inwaterlogged soils (for example, wetlands and rice

paddies) and from the digestive tracts of grazinganimals (for example, ruminants).

increased concn. from human activities include theexpansion of rice agriculture, the increased number

of livestock, the increased number of landfills, andleakage from natural gas pipelines.


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Nitrous oxide (N2O )

naturally occurring GHG but the concn.

increased significantly because of human

activities

is emitted from coal-burning power plants

and can be released from the breakdown

of chemical fertilizers in the soil.

From automobiles


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Ozone (O3 )

also a greenhouse gas.

It is important not to confuse the presence of the

ozone in the stratosphere (a good thing) with the

presence of ozone in the troposphere (a bad thing).

In the troposphere, ozone can be a major

component of urban smog damaging crops and

aggravating respiratory problems as well as

enhancing the greenhouse effect.


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Chlorofluorocarbons (CFCs)

have no natural source;

produced entirely by human activity.

been used widely as refrigerants in air conditioners,refrigerators, freezers, and heat pumps.

found in some foam plastics and used in someelectronics manufacturing.

Even though CFC production has been vastlyreduced, these compounds remain in the atmosphere

for a long time; we shall see their effects as GHGs formany years.


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Other substances emitted to the atmosphere

HydrocarbonsOther organic substances

Heavy metals such as lead

Particulate matter


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While the earth's temperature is dependentupon the greenhouse-like action of theatmosphere, the amount of heating and

cooling are strongly influenced by severalfactors just as greenhouses are affected byvarious factors.

In the atmospheric greenhouse effect, the type

of surface that sunlight first encounters is themost important factor.

Forests, grasslands, ocean surfaces, ice caps,deserts, and cities all absorb, reflect, and

radiate radiation differently. Sunlight falling ona white glacier surface strongly reflects backinto space, resulting in minimal heating of thesurface and lower atmosphere.


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Sunlight falling on a dark desert soil is stronglyabsorbed, on the other hand, and contributes to

significant heating of the surface and loweratmosphere. Cloud cover also affectsgreenhouse warming by both reducing theamount of solar radiation reaching the earth'ssurface and by reducing the amount of radiation

energy emitted into space. Scientists use the term albedo to define the

percentage of solar energy reflected back by asurface. Understanding local, regional, and

global albedo effects is critical to predictingglobal climate change.


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Atmospheric Processes

From the cycle, water is an essential

part of the earth's system.

The oceans cover nearly three-quartersof the earth's surface and play an

important role in exchanging and

transporting heat and moisture in theatmosphere.


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Most of the water

vapor in the

atmospherecomes from the

oceans.

Most of the

precipitation

falling over land

finds its wayback to oceans


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About two-thirds returns to the

atmosphere via the water cycle

the oceans and atmosphere interactextensively.

Oceans not only act as an abundant

moisture source for the atmosphere butalso as a heat source and sink

(storage).

The exchange of heat and moisture hasprofound effects on atmospheric

processes near and over the oceans.


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Ocean currents play a significant role in

transferring this heat poleward. Majorcurrents, such as the northward flowing GulfStream, transport tremendous amounts ofheat poleward and contribute to thedevelopment of many types of weatherphenomena. They also warm the climate ofnearby locations. Conversely, cold southwardflowing currents, such as the Californiacurrent, cool the climate of nearby locations.


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Energy Heat Transfer

Practically all of theenergy that reaches theearth comes from thesun. Intercepted first bythe atmosphere, a smallpart is directlyabsorbed, particularlyby certain gases suchas ozone and water

vapor. Some energy isalso reflected back tospace by clouds and theearth's surface.


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Conduction is theprocess by which heatenergy is transmittedthrough contact withneighboringmolecules.

Some solids, such as

metals, are goodconductors of heatwhile others, such aswood, are poor

conductors. Air andwater are relativelypoor conductors.

Since air is a poorconductor, most energytransfer by conduction

occurs right at theearth's surface. At night,the ground cools andthe cold ground

conducts heat awayfrom the adjacent air.During the day, solarradiation heats theground, which heats the

air next to it byconduction.


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Convection transmits

heat by transporting

groups of molecules

from place to placewithin a substance.

Convection occurs in

fluids such as water and

air, which move freely. In the atmosphere,

convection includes

large- and small-scale

rising and sinking of airmasses and smaller air

parcels.

These verticalmotions effectively

distribute heat andmoisture throughoutthe atmosphericcolumn andcontribute to cloudand stormdevelopment (whererising motion occurs)and dissipation

(where sinkingmotion occurs).

To understand the


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To understand theconvection cells thatdistribute heat over thewhole earth, let's consider a

simplified, smooth earth withno land/sea interactions anda slow rotation. Under theseconditions, the equator iswarmed by the sun more

than the poles. The warm,light air at the equator risesand spreads northward andsouthward, and the cooldense air at the poles sinks

and spreads toward theequator. As a result, twoconvection cells are formed.


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the slow rotation ofthe earth toward the

east causes the airto be deflectedtoward the right inthe northernhemisphere andtoward the left in thesouthernhemisphere. Thisdeflection of the

wind by the earth'srotation is known asthe Coriolis effect.

Radiation is thetransfer of heat energy

without the

involvement of a

physical substance in

the transmission.

Radiation can transmit

heat through a

vacuum.

E t l f th t


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Energy travels from the sun tothe earth by means ofelectromagnetic waves. Theshorter the wavelength, the

higher the energy associatedwith it. This is demonstrated inthe animation below. As thedrill's revolutions per minute(RPMs) increase, the number

of waves generated on thestring increases, as does theoscillation rate. The sameprinciple applies toelectromagnetic waves from

the sun, where shorterwavelength radiation hashigher energy than longerwavelength radiation.


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Most of the sun's radiant energy is concentrated inthe visible and near-visible portions of thespectrum. Shorter-than-visible wavelengths

account for a small percentage of the total but areextremely important because they have muchhigher energy. These are known as ultravioletwavelengths

The physical and chemical structure of theatmosphere, the way that the gases interact withsolar energy, and the physical and chemicalinteractions between the atmosphere, land, andoceans all combine to make the atmosphere an

integral part of the global biosphere.


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Overview of processes and properties

associated with global climate change

Earth's climate has always changed; it is the rateof change that is of current concern to scientists.

Carbon is critical to the biosphere and mustcontinue cycling to support life on Earth.

The carbon cycle includes sources, sinks, andrelease agents.

Carbon dioxide is an important greenhouse gas.

Living organisms in an ecosystem can haveprofound effects upon the local atmosphere.


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Understanding the major greenhouse

gases is necessary to identify the

current trends in atmosphericconcentrations and climate change.

Changes in vegetation can have

profound effects upon wind speed. Human activity has been linked with

increased greenhouse gases in the

atmosphere.


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Present Climates and Human

Activity The discovery of fossil fuels and the means of

turning the energy trapped within them into heat,

transportation, and the basis for manufacturingand construction and the global industrial

revolution that followed changed the world

forever for our species


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Since the 1800s, CO2

concentrations worldwide

have increased fromapproximately 280 ppm

(or 0.028%) to around 365

ppm (0.0365%). The

increase seems trivial, butit also means that some 3

gigatons (3 billion metric

tons) of CO2are being

added to the atmosphere

every year.


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Because CO2 is a powerful

greenhouse gas, it can beconcluded that the earth'stemperature should go upas CO2 concentrations

increase.

climatologists havedetected a steady but smallincrease in global average

temperatures over the lastfew decades, based onweather data collected allaround the world. Six of thelast ten were the hottest

years on record.


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Regardless of the cause of thewarming, we understand enough about

global climate to predict that as the

temperature goes up, the entire globalclimate system powered by heat energy

should also change, although the

magnitude and direction of the changes

are uncertain


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Future climates- The Great

Uncertainty Will the climate change for the worse because of our

actions?

In fact, no one knows for sure. Most atmospheric

scientists believe that the global climate is warmingat least partially because of a build-up of CO2 from

fossil fuel use, but what that means to humans andnatural ecosystems is largely unknown.

The climate is vastly complex and strongly influencedby many factors other than greenhouse gasconcentrations


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it extremely difficult to link any climatic events or

characteristics to a single cause.

As a result, controversy exists as to themagnitude and danger of global warming

induced by greenhouse gases.

Many scientists take the issue very seriously

and support efforts to slow or reverse the build-up of atmospheric CO2 with the expectation that

global warming will slow as a result. Others,

however, contend that CO2

may not be affecting

the climate and that the changes are part of

natural, long-term climatic cycles.


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They suggest that efforts to reduceemissions are unnecessary and dangerousto economic growth and development.

While the controversy rages, researchersaround the world continue to gather

atmospheric data, develop and refinepredictive computer models, and try toreduce the uncertainty in ourunderstanding of the earth's climate.


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With this, let us try to ponder on the

critical issues about the state of our

atmospheric environment and itsrelation to climate change, explore the

possibility of balancing the sources and

sinks (or reservoirs) of GHGs , thenature of climate change and predictions

of future changes, and the elements of

the scientific and political debates that

will ultimately determine how we respondto climate change


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Air Resources and State of the Atmospheric Environment

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Transcript of Air Resources and State of the Atmospheric Environment