Dispersal, wind

Meteorology plays an important role in determining the height to which pollutants rise and disperse. Wind speed, wind shear and turbulent eddy currents influence the interaction between the plume and surroimding atmosphere. Ambient temperatures affect the buoyancy of a plume. However, in order to make equations of a mathematical model solvable, the plume rise is assumed to be only a function of the emission conditions of release, and many other effects are considered insignificant. 

Since alcohol has dispersing and fast moving properties, it can increase the effect and speed of the herbs. Medicinal alcohol drink is often used for chronic disorders. Herbs that tonify the body, such as Ren Shen (Ginseng radix) and Gou Qi Zi (Lycii fructus), and herbs that disperse wind, damp and cold to treat Bi syndrome, such as Wu Jia Pi (Acan-thopanacis cortex), are often prepared in this way. Herbal alcohol drink is usually taken once a day in small amounts of 10-20 ml. 

Xiang Ru is the warmest of these three herbs. It is able to induce sweating, disperse wind and dampness, and release the exterior. It is especially useful... 

Cang Zhu can be selected as chief in the formula to treat a reasonably severe excess condition of wind-cold syndrome that includes the symptom of heaviness of the body. Because Cang Zhu is pungent and warm, and enters the Stomach and Spleen meridians, it can strongly dry dampness and disperse wind and cold. 

Bo He, with its strong dispersing ability, is used to increase the action of the chief in dispersing wind-heat. 

Cang Zhu is very pungent and warm. It can directly dry the dampness in the Middle-Jiao. As it can also slightly induce sweating, it can disperse wind and dampness from the superficial region of the body. 

This formula can cool the intestines, stop bleeding, disperse wind and regulate Qi. In this way it treats intestinal wind syndrome that is caused by wind-heat or damp-heat accumulation in the intestines that blocks the Qi and injures the blood vessels. The manifestations are fresh red blood before or after defecation, blood in the stool, bleeding due to hemorrhoids, a red tongue and a wiry and rapid pulse. The sign of wind in the intestines is quick-spreading blood drops before defecation. 

These six herbs are effective for treating Bi syndrome as a result of cold. They are very hot and pungent, and have strong ascending and dispersing abilities. They can strongly disperse wind, cold and dampness, intensively warm the meridians, accelerate the movement of Qi and blood, and thus effectively relieve pain. 

Sang Ye [Mori folium) Disperses wind-heat ... 

Meroney, R. N., and D. E. Neff. 1986. Heat Transfer Effects during Cold Dense Gas Dispersion Wind-Tunnel Simulation of Cold Gas Spills, Journal of Heat Transfer, vol. 108, pp. 9-15. 

Effects (functions) To disperse wind-heat, diffuse the lung to promote eruption, remove toxin and soothe the throat... 

Traditional Medicine. Traditionally considered acrid tasting and warming disperses wind and cold san feng han) and clears the nasal cavity. Chinese traditional use records date back 3000 years to the Wu Shi Er Bing Fang (Prescriptions for 52 Diseases, 1065-771 Bc). Used both internally and externally to treat nasal congestion, running nose, the common cold, and headache as well as facial dark spots also used topieally to treat toothache. 

Volatilization. The susceptibility of a herbicide to loss through volatilization has received much attention, due in part to the realization that herbicides in the vapor phase may be transported large distances from the point of application. Volatilization losses can be as high as 80—90% of the total applied herbicide within several days of application. The processes that control the amount of herbicide volatilized are the evaporation of the herbicide from the solution or soHd phase into the air, and dispersal and dilution of the resulting vapor into the atmosphere (250). These processes are influenced by many factors including herbicide application rate, wind velocity, temperature, soil moisture content, and the compound s sorption to soil organic and mineral surfaces. Properties of the herbicide that influence volatility include vapor pressure, water solubility, and chemical stmcture (251). 

Assume a continuous release of pressurized, hquefied cyclohexane with a vapor emission rate of 130 g moLs, 3.18 mVs at 25°C (86,644 Ib/h). (See Discharge Rates from Punctured Lines and Vessels in this sec tion for release rates of vapor.) The LFL of cyclohexane is 1.3 percent by vol., and so the maximum distance to the LFL for a wind speed of 1 iti/s (2.2 mi/h) is 260 m (853 ft), from Fig. 26-31. Thus, from Eq. (26-48), Vj 529 m 1817 kg. The volume of fuel from the LFL up to 100 percent at the moment of ignition for a continuous emission is not equal to the total quantity of vapor released that Vr volume stays the same even if the emission lasts for an extended period with the same values of meteorological variables, e.g., wind speed. For instance, in this case 9825 kg (21,661 lb) will havebeen emitted during a 15-min period, which is considerablv more than the 1817 kg (4005 lb) of cyclohexane in the vapor cloud above LFL. (A different approach is required for an instantaneous release, i.e., when a vapor cloud is explosively dispersed.) The equivalent weight of TNT may be estimated by... 

Introduction Gas dispersion (or vapor dispersion) is used to determine the consequences of a release of a toxic or flammable material. Typically, the calculations provide an estimate of the area affected and the average vapor concentrations expected. In order to make this determination, one must know the release rate of the gas (or the total quantity released) and the atmospheric conditions (wind speed, time of day, cloud cover). 

Parameters Affeeting Gas Dispersion A wide variety of parameters affect the dispersion of gases. These include (1) wind speed, (2) atmospheric stability, (3) local terrain characteristics, (4) height of the release above the ground, (5) release geometry, i.e. from a point, line, or area source, ( momentum of the material released, and (7) buoyancy of the material released. 

The problem with Eq, (26-60) is that the eddy diffusivity changes with position, time, wind velocity, and prevailing atmospheric conditions, to name a few, and must be specified prior to a solution to the equation, This approach, while important theoretically, does not provide a practical framework for the solution of vapor dispersion problems,... 

Sutton Micrometeorology, McGraw-Hill, 1953, p, 286) developed a solution to the above difficulty by defining dispersion coefficients, O, Gy, and O, defined as the standard deviation of the concentrations in the downwind, crosswind, and vertical x, y, z) directions, respectively, The dispersion coefficients are a function of atmospheric conditions and the distance downwind from the release. The atmospheric conditions are classified into six stability classes (A through F) for continuous releases and three stability classes (unstable, neutral, and stable) for instantaneous releases. The stability classes depend on wind speed and the amount of sunlight, as shown in Table 26-28,... 

Notice that the wind speed does not appear exphcitly in Eq, (26-61), It is implicit through the dispersion coefficients since these are a function of distance downwind From the initial release and the atmospheric stabihty conditions,... 

Worst-case atmospheric conditions occur to maximize (C). This occurs with minimum dispersion coefficients and minimum wind speed u within a stability class. By inspection of Figs. 26-54 and 26-55 and Table 26-28, this occurs with F-stability and u = 2 m/s. At 300 m = 0.3 km, from Figs. 26-54 and 26-55, <3 = 11m and <3 = 5 m. The concentration in ppm is converted to kg/m by application of the ideal gas law. A pressure of 1 atm and temperature of 298 K are assumed. 

Regardless of the source, the resultant oil slicks are essentially surface phenomena that are affected by several transportation and transformation processes. With respect to transportation, the principal agent for the movement of slicks is the wind, but length scales are important. Whereas small (i.e. relative to the slick size) weather systems, such as thunderstorms, tend to disperse the slick, cyclonic systems can move the slick essentially intact. Advection of a slick is also affected by waves and currents. To a more limited extent, diffusion can also act to transport the oil. 

Frequently, local wind systems are superimposed on the larger-scale wind systems just discussed. These local flows are especially important and may dominate when the larger-scale flow becomes light and indefinite. Local wind systems are usually quite significant in terms of the transport and dispersion of air pollutants. 

What is the approximate lowering of the centroid of a dispersing cloud of particles at 2 km from the source whose mass medium diameter is 30 ptm and whose particle density is 1 g cm in a 5 m s wind ... 

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