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32 Cards in this Set
- Front
- Back
coagulation
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collision and coalescence of 2 particles (reduce #, conserve volume)
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Condensation/evaporation
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gas condenses (changes to liquid) onto particle surface,
evaporation of liquid from particle to gas (affects volume & area, not #) |
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dissolution
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gas dissolves into water that is already on the particle surface (affects volume, not
#) |
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dissociation
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once dissolved or condensed onto particle, break into ions within particle (no effect on #) example is sea-spray acidification
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sea-spray acidification
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HNO3 + CL- = HCl + NO3-.
H2SO4 or HNO3 enter sea-spray drops, which contain NaCl, and then dissociate Cl- (NaCl) displaced by NO3- (or SO42-) to give HCl gas After all Cl- is depleted, get a build up of H+ from HNO3 (or H2SO4), which decreases pH and increases acidity (HNO3 and H2SO4 are stronger acids than HCl) Worst by coastal regions near pollution sources, where there is abundant H2SO4 and HNO3 |
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soil-particle acidification
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CaCO3 + 2HNO3 = Ca2+ + NO3- + CO2 + H2O
NO3 dissolves onto soil particles that contain CaCO3 or MgCO3 and dissociate CO32- displaced by NO3- to make CO2 gas After all CO32- is depleted, get a build up of H+ from HNO3, which decreases pH and increases acidity |
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Dry Adiabatic Lapse Rate
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negative change in temp with height for dry air, 10°C/km
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stability
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whether an air parcel will rise or not, i.e., whether pollution will mix vertically or be trapped near the surface
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Do pollutants disperse better when the air is stable or unstable?
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unstable
If parcel is warmer than Γe then it is unstable b/c will keep rising If parcel is cooler than Γe then it is stable b/c will sink (more dense) Parcel will rise at Γd until Tparcel = Te (become same temp as surrounding/environmental air) |
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If a parcel of air pollution is dry and is emitted at the ground, at what rate would the air parcel rise if it could?
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adiabatic
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What determines when a particle stops rising or if it rises at all?
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temperature of the environment, esp temperature inversions
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Define temperature inversion
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temperature increase with height
Stronger inversion has greater temp difference between cooler surface and warmer air above Why are temperature inversions important in air pollution? -trap pollutants near the surface, concentrations build up |
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large scale subsidence
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occurs within a surface high pressure system (sinking, compressing, warming air over cooler surface)
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Radiation inversion
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nighttime cooling of ground and air molecules above the ground (with warmer air further up)
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Marine Inversion
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from sea breeze (get cool air from water at surface and warmer air from land in upper branch)
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Regional (small-scale) subsidence inversion
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air compresses and warms as it moves down a mountain slope, flows above cooler air from water
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Frontal inversion
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cold air from leading edge of cold front wedges under leading edge of warm air mass (warm air mass rises above cold air mass)
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Plume: Fanning
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stable throughout
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Plume: Fumigating
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stable above, neutral/unstable below
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Plume: Looping
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unstable throughout
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Plume: Lofting
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neutral above, stable below
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Plume: Coning
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neutral throughout
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absorption
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light entering particle, increasing the internal energy of the particle
Removes that wavelength |
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scattering
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light getting redirected by particle, with no change in energy
We see these wavelengths |
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Why is the sky blue during the day?
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air molecules preferentially and repeatedly scatter blue (short) wavelengths out of the direct beam to the viewers’ eyes
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Why is the horizon red at sunset and sunrise?
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all colors are scattered and re-scattered by aerosol particles along the horizon, then B and G wavelengths are repeatedly scattered away from the line of sight by gas molecules, so that we only see the R that is transmitted to the eyes
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Do gases or particles cause most of the visibility loss in an urban area? Why?
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Particles
particles scatter and absorb more light than gases All particles scatter light and more particles absorb light than gases Only NO2, O3 and NO3 gases absorb visible light and gas scattering has a very small effect on visibility (O2 and N2 are most important, affect colors or sky and sun) |
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which processes reduce visibility the most?
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Particle scattering > particle absorption > gas absorption > gas scattering
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White clouds
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water particles scatter R, G, B (all wavelengths scattered equally), so get white
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Brown smog
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R with some G gives brown – NO2, PAH’s, and soil dust absorb B and some G,
transmit R and some G to give brown |
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Black smoke
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mainly black carbon (component of soot), absorbs all wavelengths (appear black)
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Purple stratosphere
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sulfuric acid-water particles (from volcanoes) scatter light through
stratospheric ozone layer, and ozone absorbs G and some R to give purple (B and some R) |