The AtmosphereChapter 17

100.1 km

Mach 2.9

Watch

What’s In a Breath?

78.084% (reacts with

nothing)

20.916% (allows:

burning, rust, respiration)

0.036% (a greenhouse gas

responsible for planet being warm)

0.934%

<0.03%

(Ne, He, H2, Kr, CH4, H2S)

And the Other Stuff…

Bologna, Italy

“Thickness” of the Atmosphere

• Gases zing about at 950 mph (425 m/sec)

• Gravity concentrates them near the surface– Density decreases

upward– Boiling water at

high elevation

Atmospheric Pressure

• 1-m Mercury Barometers – Inches or mm of mercury– 29.92 in = 1 atmosphere

(avg) at mean sea level– 1 atm ~ 1 bar– The weatherman– Old men and mercury

• Aneroid Barometers

Temperature in the Atmosphere

Water vapor, clouds, storms and bad weather (heated by

Earth’s radiant heat)

Air too dense to rise beyond tropopause

Oxygen Ozone (heated by Sun, absorbs

harmful radiation)

Little ozone, temperature decreases rapidly

Heated directly by high-energy X-rays and UV

radiationSpace Ship One

Ozone and You

• In stratosphere:– O2 2O O + O2 O3 (ozone)– Ozone very efficient at absorbing UV

• In troposphere:– N2 + O2 + heat 2 NO … O3

– Linked to heart disease, cancer, asthma, loss of lung function

CFCs• 1970s, used in

almost all refrigerators, air conditioners, propellants in aerosol cans

• Stable• Work their way

Into atmosphere and

Destroy ozone

Come Back!

…

The Ozone Hole

• Not literally a “hole”—more like a male pattern baldness

Other Pollutants

• Donora, PA– 27-31 October 1948– Smog settled over city

• Sulfuric acid, nitrogen dioxide, fluorine trapped in valley by stagnant air

• 20 dead, 800 animals respiratory illnesses

• Plants dead in half-mile radius of steel, zinc works

• 1/3 of town’s 14,000 people were sick

Donora at noon, Oct. 29, 1948

Clean Air Act of 1970

• Amendment to CAA of ’63

Smog over Shanghai

Primary Standards to protect “sensitive” groups: elderly, children, ashtmatics

Secondary Standards to protect against decreased visibility, damage to animals, vegetation, crops, and buildings

Superscripts=exceptions1/y

Advancing the Clean Air Act

• 1970 Amendments:– Environmental Protection Agency

(EPA) to determine the limit of industrial pollutants

– Controlling auto emissions by 90%

• 1990 Amendments:– Contributors to ozone

depletion phased out– Rules on toxic waste

and acid rain

The Burning of Hydrocarbons

• Form CO2 and/or water during burning

Impurities and Incomplete Burning

– Benzene, methane (CHBenzene, methane (CH44), carbon monoxide (CO), ), carbon monoxide (CO),

sulfur dioxide (SOsulfur dioxide (SO22), nitrogen oxide (NO), nitrogen oxide (NO22))

– Mercury in rivers near Kittanning, PA: Mercury in rivers near Kittanning, PA: • Fish at 3.1-19x concentration of mercury than store-boughtFish at 3.1-19x concentration of mercury than store-bought• Mercury linked to neurological disordersMercury linked to neurological disorders• 5-8x EPA’s acceptable risk depending on age5-8x EPA’s acceptable risk depending on age

– Minamata DiseaseMinamata Disease

Actually, the plant in Seward, PA

Acid Rain

• In moist air, you get sulfuric and nitric acids which dissolve in water vapor, fall as rain

• pH 7.0 (neutral)– Normal rain pH ~5.7

due to CO2

– 1986, in southern CA a fog reached pH = 1.7

Acid RainAcid Rain

• Too weak to irritate human skin but is Too weak to irritate human skin but is devastating to delicate organisms and rockdevastating to delicate organisms and rock– Damages mountain forestsDamages mountain forests

• Germany 1982-1995: 8% unhealthy to 50% SICK Germany 1982-1995: 8% unhealthy to 50% SICK

– Acidifies lakes causing massive fish killsAcidifies lakes causing massive fish kills

Acid-rain on forest in Jizera mountains of Czeck Repulic Actually, acid-mine drainage (this is extreme limit)

• Rapidly weathers stone monuments

• U.S. several billion $/yr repairing damage

Other Toxic Volatiles

• Chemicals that readily evaporate into air– Pesticides – some is carried off by wind– Dioxin – formed in backyard burn barrels or

wherever plastic polyvinyl chloride is burned• Gets into grass, ruminants• We eat meat: 0.0000000001 g/day• EPA: “at or near levels associated

with adverse health effects”• Could cause cancer, birth defects,

reproductive and immune disorders

V child, blamed on Agent Orange

Particulates and Aerosols

• Particulate: Small pieces of solid matter

• Aerosols: Small particles suspended in air– Fly ash: Smoke, soot, clay/stuff that can’t burn