Lecture 11 Flashcards
What are the 3 flavors of smog?
Prehistoric, Historic, Modern.
What does PM mean?
Particulate matter aka aerosols.
What does VOC mean?
Volatile Organic Compound.
What are the sources of VOC?
Unburned gasoline and similar fluids/trees containing isoprene and alpha-pinene.
Stratospheric Ozone
Protects life from harmful effects of UV radiation from sun.
Upper Tropospheric Ozone
An effective greenhouse gas. Increases in concentrations may have already had significant climatic impact.
Ground-level Ozone
Reacts with living tissue. Concentrations above 50-70 ppbv decrease net productivity of crops, trees, etc.
What is the most obvious indications of smog?
Haze.
What is size distributions?
Expressing the abundance of atmospheric PM or aerosols via size and number per unit volume.
Atiken Nuclei
aka Ultra fine particle D<0.1 ; Are rapidly removed via coagulation onto larger particles because of their relatively high Brownian-motion velocities.
Large or ‘Accumulation Mode’ Aerosol
0.1 micrometer<1 micrometer; so-called because of their tendency to accumulate in the atmosphere due to their relatively long lifetime.
Giant or Coarse Aerosols
D>1 micrometers; Are rapidly removed via sedimentation.
How does PM affect climate?
Either the direct effect or the indirect effect
Direct Climatic Effect
Accumulation mode areosols scatter visible radiation (i.e. from haze and fog). They thus tend to backscatter some portion of the incoming solar radiation back to space. Decreasing the net heating from absorption of solar radiation and thus causing a cooling in climate.
Indirect Effect
Accumulation mode aerosols act as cloud condensation nuclei (CCN). The more CCN, the more cloud droplets in a cloud; generally, # of cloud droplets ~ # of CCN present in air from which cloud formed.
