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