Atmosphere

Properties of the Atmosphere

• Provides us with oxygen

• Protects from UV rays

• Transports/recycles water

• Burns up meteors

• Controls climate

• Made of 78% nitrogen, 21% oxygen, and

1% other gases

Nitrogen

• Most organisms can’t use nitrogen in the atmosphere

• Needs to be “fixed” first

• Nitrogen-fixing bacteria convert nitrogen into a usable form

Oxygen

• Early Earth had no oxygen

• Photosynthetic microorganisms built up oxygen gas• Released during photosynthesis

Relative Humidity

• Ratio of water vapor in air to the maximum amount it can hold at that temperature

• Ex. 50% relative humidity means that the air is holding 50% of the water it can hold at that temperature

• Warm air holds more water than cold air• Condensation – when warm air cools quickly

• Creates water droplets or ice crystals

• Cloud formation• Water vapor condenses on salt crystals, smoke, or dust

Air Temperature and Pressure

• Temp varies on Earth because sun’s rays strike some areas more directly

• Pressure measured by barometer

• Pressure decreases as altitude increases

Layers of the Atmosphere

Troposphere oxygenweatheralmost all cloudstemp decreases with altitude

Stratospheretemp increases with altitudeozone layer(ozone found in troposphere is unnatural and considered pollutant

Mesospheremeteoroids burn up

Thermosphereaurora borealis

Troposphere and Weather

• Weather – day-to-day patterns

• Climate – averages over long periods of time

Heat Transfer

• Heat always moves from hot to cold objects

• Radiation • No direct contact• Dark objects absorb more radiation than

objects light in color• Light objects reflect radiation

• Conduction• Transfer of heat directly

• Convection• Transfer of heat through movement of currents within a fluid

Convection Currents

Air Masses and Fronts

Sources of Air Pollution

• Emissions of smoke or soot or emissions of gases like sulfur dioxide and carbon monoxide• Natural processes

• Wind creating dust storms

• Volcanoes erupting

• Forest fires

• Human activities• Can make natural pollution worse

• Most air pollution from combustion of fossil fuels

• Industries, cars, energy production

• Primary air pollutants• Directly released into troposphere

• Can harm on their own or reacts with other products to cause damage

• Carbon monoxide, sulfur dioxide, nitrogen dioxide

• Secondary air pollutants• When primary air pollutants react chemically with other

substances

• Tropospheric ozone, sulfuric acid

Air Pollution Affecting Health

• Respiratory Problems• Particles irritate air passages and lungs

• Asthma, bronchitis, emphysema

• Issues with Carbon Monoxide• Oxygen usually binds to hemoglobin to be carried by red

blood cells through body

• Carbon monoxide binds to hemoglobin (replacing oxygen) so oxygen not carried through body

• Headaches, nausea, fatigue, heart damage, death

• Cancer• Soot or benzene (found in car exhaust)

Smog• Smoke + fog

• Industrial smog• Soot + sulfur compounds + water droplets

• Less common in developed nations because of new technologies and government regulations

• Photochemical smog• Needs light

• Sunlight interacts with pollutants to create a brown haze

• Tropospheric ozone most abundant pollutant• Damages living tissue and plant leaves

• Car/truck exhaust main source of pollutants

• Earth warms air, warm air rises and disperses pollutants

• Temperature inversion • Layer of cooler air located beneath warmer air

• Air doesn’t rise and mix

• Pollutants stay near the surface

Acid Deposition• Acids that settle to the surface of Earth

• Acid pH below 7

• Most rain is slightly acidic (5.6)

• Some areas as low as 4.3

• Comes from burning fossil fuels sulfur dioxide and nitrogen oxides

• Mix with oxygen and water to form sulfuric acid and nitric acid

• Can fall in areas far from where the pollutants were produced

Effects of Acid Deposition

• Harm ecosystems and structures

• Kills trees

• pH in lakes too low, plants and fish die

• Erodes stone buildings and statues

The Clean Air Act

• Goal• Protects and improves quality of air

• Reduce emissions

• Limits release of pollutants

• Provisions• Limits emissions from vehicles and industries

• Set standards for air quality based on amount humans can tolerate without being harmed

• People can sue industries that break rules

• Set aside funds for pollution control

• Worst air pollutants down 57%

• Vehicles create less pollution• Catalytic converter reduces pollutants in emissions

• Cleaner gasoline less lead

• Industries and power plants required to reduce pollutants released• Scrubbers remove pollutants or change them chemically before

leaving smokestacks

Ozone

• Ozone hole found over Antarctica between August and October

• CFCs found as a reason for ozone depletion• Used in aerosol cans

• Montreal Protocol• Treaty called for major cuts in CFC production

• Reduced by 95% since 1980s

• Ozone layer is recovering