Diffusion of Stack Gases in Very Stable Atmospheres

Barad, Morton L.

doi:10.1007/978-1-940033-03-7_2

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…The exhaust plumes from power plants provide an excellent example. As shown by Barad (1951) the diffusion of stack gases in ý-ery stable atmospheres should be treated as comitLg from a planar source of finite concentration rather than as from a point cf infinite concentration. Barad's treatment agrees we>' with observations on power plant plumes which remain aloft and move with the wiud, rarely joining the main ice fog before they dissolve (Figs.…”

Section: Remedial Actionmentioning

confidence: 99%

Ice Fog: Low Temperature Air Pollution Defined With Fairbanks, Alaska as Type Locality

Benson¹

1965

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Stable pressure systems over interior Alaska sometimes produce prolonged, extreme (below -40 0 C) cold spells at the surface.The meteorological conditions responsible for two such cold spells are discussed in detail in Appendix A, where it is shown that the rate of radiative cooling of the air is enhanced by suspended ice crystals which are themselves a result of the initial cooling.Radiation fogs formed during the onset of cold spells are generally of short duration because the air soon becomes desiccated. These fogs consist of supercooled water droplets until the air temperature goes below the "spontaneous freezing point" for water droplets (about -40°C); the fog then becomes an ice crystal fog, or simply "Ice Fog`ý.During the cooling cycle water is gradually condensed out of the air until the droplets freeze.At this point there is a sharp, discontinuous decrease in the saturation vapor pressure of the air because it must be reckoned over Ice rather than over water.The polluted air over Fairbanks allows droplets to begin freezing at the relatively high temperature of -35*C. Between -35 and -40 0 C the amount of water vapor condensed by freezing of supercooled water droplets is 3 to 5 times greater than the amount condensed by l°C of cooling at these temperatures.This results in rapid and widespread formation of ice fog (Appendix B) which persists in the Fairbanks area as long as the cold spell lasts. The persistence of Fairbanks ice fog depends on a continual source of moisture (4.1 x 106 Kg H 2 0 per day) from human activities within the fog.Ice fog crystals are an order of magnitude smaller than diamond dust, or cirrus cloud crystals, which in turn are an order of magnitude smaller than comnnon snow crystals (0.01, 0.1 and 1 to 5-=n respectively). The differences in size are shown to result from differences in cooling rates over 5 orders of magnitude.Host of the ice fog crystals have settling rates which are slower than the upward velocity of air over the city center.The upward air movement is caused by convection cells driven by the 6VC "heat island" o~er Fairbanks.This causes a reduced precipitation rate which permits the density of ice fog in the city center to be three times greater than that in the outlying areas.The inversions which occur during cold spells over Fairbanks begin at ground level and are among the strongest and most persistent in the world. They are three times stronger than those in the inversion layer over Los Angeles.Thus, the low-lying air over Fairbanks stagnates and becomes effectively decoupled from the atmosphere above, permitting high concentrations of all pollutants.The combustiog of fuel oil, gasoline, and coal provides daily inputs of: 4.1 x 10 kg C02; 8.6 x 103 kg S02; and 60, 46 and 20 kg of Pb, Br and Cl respectively, into a lens-like layer of air resting on the surface with a total volume less than 3 x 109 m 3 .The air pollution over Fairbanks during cold spells couldn't be worse, because the mechanisms for cleaning the air are virtually eliminated while all activi...

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Section: Remedial Actionmentioning

confidence: 99%

Ice Fog: Low Temperature Air Pollution Defined With Fairbanks, Alaska as Type Locality

Benson¹

1965

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“…The BNL curve is derived from the same equation, but in this case, n -1.0, C z = 0.025 and C y = 0.40. The Barad 1951 curve is adapted from his 1951 publication. It is apparent that the BNL and Barad plots have the correct slope to match that of the actual data, while the Sutton line shows too rapid a decrease.…”

Section: Gsec Unitsmentioning

confidence: 99%