Cloud travel

Acid rain. Natural (unpolluted) precipitation is naturally acidic with a pH often in the range of 5 to 6 caused by carbonic acid from dissolved carbon dioxide and sulfurous and sulfuric acids from natural emissions of SO and H2S. Human activity can reduce the pH very significantly down to the range 2 to 4 in extreme cases, mainly caused by emissions of oxides of sulfur. Because atmospheric pollution and clouds travel over long distances, acid rain is not a local problem. The problem may manifest itself a long way from the source. Problems associated with acid rain include ... 

Vaughan, L. M. R. W. McMullen "Intermediate-scale aerosol cloud travel and diffusion from low-level aerial line releases." Technical Report No. 97, U. S. Army Chemical Corps Contract No. DA-42-007-CML-543, 1963. 

The time required for actuation is a critical issue. Cloud travel time to sensitive areas can be achieved in a few seconds for jet releases and in a few minutes for refrigerated releases. Therefore, to be effective, water curtains must be designed to be activated within a short time of the onset of a release. 

The purpose of the Berkeley project was to understand how gas clouds traveled and dissipated over various terrains and micro-meteorological conditions. They developed new instruments to make such studies. If an electrical current flows through a platinum wire, it may become red hot, and its temperature was easily measured. If air flowed over the hot wire, its temperature was lowered, and the faster the air flows the more the temperature is lowered. The Berkeley group measured wind speed by use of this hot-wire anemometer. If air contains some butane, for example, the hot platinum wire burns the butane, and the heat of combustion causes... 

Each man should provide himself with data sheets and data boards beforehand. Be sure to record the data, shoot number, and time of burst on each sheet. Any visual impressions of cloud travel should also be noted on data sheets immediately after the shoot. Check watches with that of the Technical Director before the burst. 

The reason for this form of profile is because of the essentially Gaussian nature of large scale turbulent eddying motions. The profile is not greatly affected by mean velocity gradients when the cloud travels over flat or undulating surfaces (e.g. Pasquill and Smith, 1983 [484] Hunt et al 2002 [294]). 

Ground deposition corresponding to the cloud-dosage at any distance in Figs. 1 and 2 can be calculated by multiplying the cloud dosage by the appropriate value of Vg. However, as the cloud travels downwind, it will be progressively depleted of material by deposition. The effect can, of course, be... 

A case study is performed assuming an instantaneous release of the toxic liquid acrylonitrile from a rail tankwagon. After the release of the toxic liquid a pool of 600m is formed from which evaporation occurs, leading to a vapour cloud. This vapour cloud travels with the wind and disperses. The degree of dispersion is determined by the wind speed, the stability of the atmosphere and the surface roughness. The stability of the atmosphere is indicated by the pasquill-stabUity class. By day, the most common atmospheric stability class is class D and a wind speed of 5 m/s is assumed, this weather condition is abbreviated with D5. At night class F is the most common atmospheric stability, associated with a wind speed of 1.5 m/s this weather condition is abbreviated as FI.5. The evaporation and dispersion calculations are performed with EFFECTS 7.6. A neutral gas model is used for the dispersion calculations. 

A variety of treatment methods was checked. The most effective was the rapid addition of Kemsol (anhydrous sodium sulfate) to the pool. It was observed that the initial vapor cloud traveled 6 to 7 km downwind and dispersed very slowly. The conditions of the tests were very humid (relative humidity 84%). It took 13 minutes of application of Kemsol to suppress the fumes (the rate of application was not specified). Treatment of the cloud with water spray seemed to be ineffective. Addition of water to the pool produced very large quantities of fume, and this method appeared to be suitable only for handling small spills. After the trial, the concrete tray was eroded by 2 mm and the asphalt tray by 25 mm. It seemed that the upper surface of the trays was rapidly attacked, but at depth erosion proceeded very slowly. 

C2 and n are Sutton s parameters and the values used In this analysis are shown In Table F-3 t a time of cloud travel to potot x. 

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