Air Pollution Dispersion LabTim Ellis, Ph.D., P.E.
CE 326 Principles of Environmental EngineeringDepartment of Civil, Construction and Environmental Engineering
Iowa State UniversitySpring 2008
ATMOSPHERIC CONDITIONS WHICH AFFECT AIR POLLUTION
Wind direction and speedCloud cover radiation reaching earth
temperature profile turbulencePrecipitation
Neutral StabilityNeutral Stability
UnstableUnstable
StableStable
Inversion in Los Angeles, CA
Inversion at Four Corners power plant
Fig 7-17Fig 7-17: Land Breeze during night: Land Breeze during night
Fig 7-18Fig 7-18: Land Breeze during day: Land Breeze during day
Fig 7-19Fig 7-19: Effect of lake breeze on plume dispersion: Effect of lake breeze on plume dispersion
Fig 7-21Fig 7-21: Plume dispersion coordinate system: Plume dispersion coordinate system
22
,0, 5.0exp5.0expzyxy
Hxy SH
Sy
uSSE
Fig 7-22Fig 7-22: Horizontal dispersion coefficient: Horizontal dispersion coefficient
Fig 7-23Fig 7-23: Vertical dispersion coefficient: Vertical dispersion coefficient
894.0axsy
fcxs dz
PLUME RISEPLUME RISE
d
TTTp
udvH
s
ass ))(1068.2(5.1 2
Fig 7-24Fig 7-24: Effect of elevated inversion on dsipersion: Effect of elevated inversion on dsipersion
sszz = 0.47 ( L - H ) = 0.47 ( L - H )
Building Downwash
Building Downwash
Building Downwash
Building Downwash