Unit 12: The Atmosphere

Unit 12: The Atmosphere

Case study: Charging Toward a Cleaner London

killer smog caused by temperature inversion

Atmosphere

the thin layer of gasses surrounding Earth; 78% nitrogen, 21% oxygen

Relative Humidity

ratio of water vapor that the air contains to the maximum amount it can hold

Air Pressure

force exerted by air on the area below it; decreases with altitude and storms; measured using Barometer

Barometer

measures air pressure

Layers of atmosphere (closest to farthest out)

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

Troposphere

humans live here; weather; movement of air; heat is transferred

Stratosphere

ozone layer; absorbs and scatters UV rays

Mesosphere

meteoroids burn up

Thermosphere

disturbances produce aurora borealis (Northern lights)

Driving force behind air movement in the troposphere?

heat transfer

Ways of heat transfer in troposphere

radiation, convection, conduction

Radiation

transfer of energy through space ex. heat coming off stove

Conduction

transfer of heat directly between 2 objects that are in contact ex. stove makes pan hot

Convection

transfer of heat by the movement of currents within a fluid; plays role in climate systems ex. boiling water in a pot

Warm air is?

less dense than cool air and rises

How do Convection Currents work?

air near the surface of Earth heats up, rises, then cools and sinks which generate currents

What do Convection Currents cause?

wind and heat to move throughout the atmosphere creating weather patterns

Air Masses

large bodies of air with similar properties

Fronts

boundaries between air masses that differ in temp and moisture

Warm Front

warm air pushes up, cold is at bottom; light rain

Cold Front

cold air pushing against warm air; blizzards/snow/tornados; heavy rain

Sources of air pollution?

natural and human

Air Pollution

release of damaging material into the air

Natural air pollution

windblown dust, particles in volcanic eruptions, smoke and soot from fire

Human air pollution

burning fossil fuels (directly or indirectly) ex. vehicles and factories

Fossil Fuels

carbon containing fuel made from the remains of living things; greatest source of air pollution; create emissions ex. gas, coal

Emissions

substance released into atmosphere ex. soot, smoke, sulfur dioxide, carbon monoxide

2 types of air pollutants?

primary and secondary

Primary Air Pollutant

released directly into the atmosphere ex. soot, forest fire

Secondary Air Pollutant

formed when primary pollutants react chemically with other substances ex. sulfuric acid, tropospheric ozone

How air pollutants affect health?

o Lung irritation and respiratory illnesses ex. asthma
o Carbon monoxide interferes with body's ability to deliver oxygen to cells
o Trace amounts of some may contribute to cancer ex. benzene, soot

Monoxide vs the body

does not allow oxygen to bind to hemoglobin

Smog

an unhealthy mix of air pollutants that forms over cities; combination of the word "smoke" and "fog"

Industrial Smog

comes from industrial sources; grey ex. soot, sulfur, water vapor

Photochemical Smog

mostly in tropospheric ozone created when primary pollutants from vehicle exhaust react to sunlight; yellow

How does Temperature Inversion affect air pollutants?

normally pollutants are carried up with warm air, but with a temperature inversion, the warm air sits over cool air, trapping the pollutants near Earth's surface

Acid Deposition

acid falls as particles, or dissolves in precipitation, lowering the pH of the precipitation (rain, sleet, or snow); harms forest and lakes and damages human structures

SA: Acid Deposition diagram

label primary and secondary pollutants

Acidic pH

below 7

How is acid in Acid Deposition formed?

sulfur dioxide and nitrogen oxides are primary pollutants that react with water, oxygen, and other chemicals

The Clean Air Act

After being revised several times, it protects us by improving air quality through:
o Limits on emissions of pollutants
o Setting standards for air quality
o Suing industries that break the rules
o Providing funding for pollution control

Accomplishments of The Clean Air Act

o Catalytic converters (present in all cars since 1975) have reduced vehicle emissions
o Lead has been phased out of gasoline
o Industries and power plants have reduced releases of pollutants by using scrubbers

Scrubbers

remove or alter chemicals before they leave factory smokestacks

Ozone

pollutant in the troposphere BUT in the stratosphere it creates a protective barrier against UV radiation

Chlorofluorocarbons (CFC)

chemicals found in everything from aerosol cans to refrigerators; destroyed ozone causing an "ozone hole" to form over Antarctica

Ozone Hole

allows more UV radiation to reach Earth's surface potentially increasing cases of skin cancer; in Antartica

How is the Ozone Hole being fixed?

cutting CFC production (Montreal Protocol)

Montreal Protocol

international treaty signed in 1987 that has cut CFC production by 95% since the 1980s

Ozone Hole now?

ozone levels in the stratosphere have begun to stabilize and the hole will likely start to disappear