GY205 Weather and Climate

1
GY205 Weather and Climate

• Lecture 7

2
Air Pollution

• Undesirable gases and particulates introduced by
  human activities
• Primary pollutants directly enter the air
• Secondary pollutants are formed by chemical
  reactions after a substance has entered the air

3
Particulates

• A.k.a. aerosols
• Tiny solids and liquid droplets
• Source combustion (soot/smoke, engine exhaust)
• Effects reduces visibility respiratory and
  cardivascular disease (especially finest
  particles)
• Removed by settling and scavenging

4
Oxides of Carbon

• Carbon monoxide (CO) and carbon dioxide (CO2)
• Colorless, odorless gases
• Source incomplete combustion in cars that need a
  tune-up
• Effects CO2 is a greenhouse gas CO is toxic,
  hemoglobin absorbs it instead of O2,

5
Oxides of Sulfur

• Sulfur dioxide (SO2) and Sulfur trioxide (SO3)
• Colorless gases, stink link rotten eggs
• Sources SO2 from burning fossil fuels SO3
  secondary from SO2
• Effects Corrosive respiratory problems acid
  precipitation

6
Acid Precipitation
7
Oxides of Nitrogen

• Nitrogen dioxide (NO2)
• Yellowish-reddish brown, pungent gas
• Sources high-temp combustion causes NO to react
  with O in the air vehicles and power plants
• Effects lung damage, reduced immunity

8
Volatile Organic Compounds (VOC)

• A.k.a. hydrocarbons
• Gases methane, butane, propane, octane
• Sources industry and cars (incomplete
  combustion, evaporation while filling up)
• Effects no evidence of health effects reacts
  with sunlight to produce smog and secondary
  pollutants

9
Smog

• Two types London-type smog and L.A.-type smog
• London-type smoke fog/damp air
• L.A.-type photochemical smog, produced by
  reactions caused by solar radiation interacting
  with NO and VOC
• Ozone (O3) is main component of L.A.-type
• O3 causes respiratory distress, lung damage,
  reduced immunity to lung diseases

10
Weathers Effects on Pollution

• Faster and more turbulent winds dilute pollutants

11

• Inversions cap convection and trap pollutants

Surface inversion caused by nighttime radiational
cooling
Inversion caused by subsidence associated with
high pressure
12
Urban Heat Islands

• Built-up areas are generally warmer than the
  surrounding countryside
• Most noticeable at night and during the winter
• Caused by building materials and human activities

Heat island of Washington, DC during winter
13
GY205 Weather and Climate

• End of Lecture 7