Greenhouse effect

Greenhouse Gases Water vapor (H2O) - evaporation Carbon Dioxide (CO2) – burning fossil fuels Nitrogen oxides (NOx) – vehicle exhaust Sulfur oxides (SOx) – factory pollution Ground level Ozone (O3) - Vehicles CFC’s - aerosols

Photochemical Smog Chemical reaction that is activated by light Example: Nitrogen and Oxygen N2 + O2  2NO 2NO + O2  2NO2 (smog) 3NO2 + H2O  2HNO3 + NO NO2 + UV radiation  NO + O O + O2  O3 (ground-level o-zone)

Photochemical Smog Ozone levels peak on hot days during rush hours and in the early afternoon NOx is released from cars during this time What do London, Pittsburgh, and Chicago have in common during the Industrial Revolution? Burned LARGE amounts of coal and oil which released SOx into the atmosphere

Pittsburgh, Pennsylvania Circa. 1906

Industrial Smog Pollution from factories and coal power plants Sulfur dioxide (SO2), sulfuric acid (H2SO4), suspended particulates Chemistry of coal: C + O2  CO2 & 2C + O2  CO2 & *soot S + O2  SO2; lead sulfides from minerals 2SO2 + O2  2SO3 SO3 + H2O  H2SO4 H2SO4 + 2NH3  *(NH4)2SO4

Smog Frequency and severity of smog depends on: Climate Topography (Mountains) Population density Industry Precipitation “cleans” the air Winds bring fresh air, mixes the atmos., and move the smog Tall buildings, Hills and mountains, and high temperatures help smog formation

Smog Layer over Los Angeles Warm Air Inversion Layer Temperature inversion: when temperatures RISE in the troposphere