1. The Atmosphere Ch. 20 & 21 Living in the Environment, Miller (2005 )

2. Structure & Composition of the Atmosphere Part 1

3. Electromagnetic Spectrum

5. The Earth’s Atmosphere Temperature profiles separate the layers The layers filter out the most energetic damaging solar radiation

6. http://www.nas.nasa.gov/About/Education/Ozone/radiation.html Mesosphere Stratosphere Troposphere Thermosphere

7. When considering the effect of UV radiation on human health and the environment, the range of UV wavelengths is often subdivided into: - UVA (400–320 nm) - Long Wave or "blacklight“ - UVB (320–280 nm) - Medium Wave - UVC (< 280 nm) - Short Wave or "germicidal"

8. Thermosphere (Ionosphere) –temperature  as altitude  (-90 ºC to 1200 ºC) –b/c solar radiation is most intense at the high altitudes –extremely low pressure (<0.01 atm) means very few collisions –charged ions exist by themselves (“ionosphere”) NO, N, O, N 2 +, O + are stable

9. Mesosphere –temperature  as altitude  (-2 ºC to -90 ºC) –temperature increases w/ decreasing altitude because gas pressure increases by 10 5 (more gas to absorb) –O 2 and O 3 absorbs some of the UV radiation that is not absorbed by the thermosphere

10. Stratosphere –temperature  as altitude  (-60 ºC to -2 ºC) –temperature inversion keeps troposphere and stratosphere from mixing –elevated levels of ozone Troposphere –temperature  as altitude  (14 ºC to -60 ºC) –warmest near Earth’s surface (heat capacity of surface) –mostly N 2 (78%) and O 2 (21%) because UV radiation is absent

11. “GOOD” Ozone “BAD” Ozone

12. “good” ozone “bad” ozone

13. Sources of Outdoor (Ambient) Air Pollution Part 2

14. Outdoor Air Pollution Pollutants come from natural sources –dust particles, VOCs released from plants, plant decay, forest fires, volcanic eruptions, sea spray –most sources are spread out and rarely reach harmful levels Pollutants come from anthropogenic (man- made) sources –burning of fossil fuels stationary sources = factories, power plants mobile sources = cars

16. Table 20-1 Major Classes of Air Pollutants Class Carbon oxides Sulfur oxides (SO x ) Nitrogen oxides Volatile organic compounds (VOCs) Suspended particulate matter (SPM) Photochemical oxidants Radioactive substances Hazardous air pollutants (HAPs), which cause health effects such as cancer, birth defects, and nervous system problems Examples Carbon monoxide (CO) and carbon dioxide (CO 2 ) Sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ) Nitric oxide (NO), nitrogen dioxide (NO 2 ), nitrous oxide (N 2 O) (NO and NO 2 often are lumped together and labeled NOx) Methane (CH 4 ), propane (C 3 H 8 ), chlorofluorocarbons (CFCs) Solid particles (dust, soot, asbestos, lead, nitrate, and sulfate salts), liquid droplets (sulfuric acid, PCBs, dioxins, and pesticides) Ozone (O 3 ), peroxyacyl nitrates (PANs), hydrogen peroxide (H 2 O 2 ), aldehydes Radon-222, iodine-131, strontium-90, plutonium-239 (Table 3-1, p. 49) Carbon tetrachloride (CCl 4 ), methyl chloride (CH 3 Cl), chloroform (CHCl 3 ), benzene (C 6 H 6 ), ethylene dibromide (C 2 H 2 Br 2 ), formaldehyde (CH 2 O 2 )

17. Categories: –Primary Pollutants emitted directly into troposphere in a potentially harmful form –Secondary Pollutants some primary pollutants react with others or with air to form new pollutants Prevailing winds can transport long-lived pollutants to other geographic areas

19. Criteria Pollutants –government-mandated standards that set maximum allowable atmospheric concentrations for 6 conventional air pollutants –National Ambient Air Quality Standards (NAAQS) of Clean Air Act –CO, NO 2, SO 2, PM, O 3, Lead –Most scientists would also add VOCs to this list because of their role in the formation of photochemical smog –Many would add CO 2 too