control of air pollution

Control of Air Pollution

adapted to HTML from lecture notes of Prof. Stephen A. Nelson Tulane University

Control of Air Pollution
Smog
Air Inversion
Global Warming
Greenhouse Gases
Acid Rain
Sources
 

Control of Air Pollution

Automobiles Coal

Smog

Air Inversion

inversion1.gif

A similar situation arises in mountain valleys where warm air overlies the colder air which accumulates in the valleys.

inversion2.gif

Also, cities tend to form featuers known as heat islands or dust domes, which tend to collect warm air filled with pollutants, and help spread it out over nearby suburbs.

hear-dome.jpg


Global Warming

solar-radiation.gif


  • If there were no greenhouse effect, the average temperature on the earth would be - 20C with huge fluctuations in a 24 hour period.
  • When visible light from the sun hits the earth some is absorbed, heating the earth.   The heated earth gives off infrared radiation characteristic of the 25C temperature. This longer wavelength infrared radiation  is then reradiated back into space. Some of the  infrared radiation, however, is  trapped (absorbed) by greenhouse gases. This is known as The Greenhouse Effect.

  • There are several gases which cause the greenhouse effect, and whose concentrations determine the amount of heat retained by the earth. Primary among these are water vapor, carbon-dioxide and methane. The chart below shows how the concentration of CO2 in the atmosphere has changed in the last 40 years:

     co2-concentration.gif


    Gases contributing to Anthropogenic Greenhouse Effect
    Gas  Rate of Increase 
    (% per year) 
    Relative Contribution(%) 
    CO2  0.5  60 
    CH4  15 
    N2O  0.2 
    O3  0.5 
    CFC-11 
    CFC-12 



    Scientific Consensus on Global Warming
    Statement  Consensus 
    Fundamental Physics  90+% 
    Added greenhouse gases add heat  90+% 
    Added gases are anthropogenic  90+% 
    Reduction of uncertainty will require a decade  90+% 
    Full recovery will require many centuries  90+% 
    Large stratospheric cooling  90+% 
    Precipitation will increase  90% 
    Reduction of sea ice  90% 
    Warming in arctic  90% 
    Rise in sea level  90% 
    Local details of global change 
    Tropical storms increase 
    Details of next 25 years 



    Greenhouse Gases

  • Carbon Dioxide (CO2): Roughly 60% of total
  • Methane (CH4): 15% of total
  • Acid Rain


    Effects of Acid Rain