introduction of undesirable gases and particulates by humans.
emitted directly into the atmosphere
result from one or more chemical transformations.
Air pollution in urban areas is often called smog.
what produces secondary pollutants
Primary pollutants in combination with sunlight can produce secondary pollutants. Examples are Ozone and Pan (Peroxyacetyl nitrate)
effects of strong winds on pollutants
Disperse pollutants from source Turbulence mixes polluted air with surrounding air
determines the extent to which vertical motions will mix the polluted air with cleaner air.
is the distance between the earth?s surface and the extent of convection
pollution in LA is related to
subsidence inversions Cool ocean temperatures Mountains that surround the city and prevent smog from dispersing inland
Meteorological Factors Affecting Air Pollution
The amount of pollution is a function of the amount of contaminants emitted. However, weather factors can affect pollution concentrations.
1970's clean air act
Set standards for four pollutants: sulfur dioxide carbon monoxide nitrogen oxides Particulates (lead added later)
1990 cleaner air act amendments
In 1990, Congress passed the Clean Air Act Amendments. Tighter controls on air quality Lower limits on auto emissions Require the use of cleaner burning fuels Limits on CFC?s and ozone depleting compounds.
URban Heat Islands
City cores are typically warmer than surrounding rural environments by up to 10oC under clear skies and weak wind conditions
UHI is primarily a nighttime phenomenon,
can occur throughout the year,
defined as any change in some statistical property like mean temperature, precipitation, and wind
defined as the statistical properties of the atmospheric variables like temperature, precipitation, and wind
warmer temperatures less snow/ice lower surface albedo more absorbed solar radiation higher surface temperature
negative feedback mechanism
opposes or offsets the initial change
negative feedback mechanism example
cloud coverwarmer temperatures more evaporation, higher atmospheric moisture content, & more clouds clouds increase albedo & reflect solar radiation less energy to heat the surface & cooler temperatures
reduce emissions of radiatively active gases Kyoto Treaty
build sea walls around coastal cities develop aquaducts to bring water to newly dry areas
engineer the earth?s atmospheres and oceans to reduce climate change
is reduction of greenhouse gas emissions to prevent dangerous climate change
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