Cloud simulation chamber

Laboratory simulations of aqueous-phase chemical systems are necessary to 1) verify reaction mechanisms and 2) assign a value and an uncertainty to transformation rates. A dynamic cloud chemistry simulation chamber has been characterized to obtain these rates and their uncertainties. Initial experimental results exhibited large uncertainties, with a 26% variability in cloud liquid water as the major contributor to measurement uncertainty. Uncertainties in transformation rates were as high as factor of ten. Standard operating procedures and computer control of the simulation chamber decreased the variability in the observed liquid water content, experiment duration and final temperature from 0.65 to 0.10 g nr3, 180 to 5.3 s and 1.73 to 0.27°C respectively. The consequences of this improved control over the experimental variables with respect to cloud chemistry were tested for the aqueous transformation of SO2 using a cloud-physics and chemistry model of this system. These results were compared to measurements made prior to the institution of standard operating procedures and computer control to quantify the reduction in reaction rate uncertainty resulting from those controls. 

The cloud chemistry simulation chamber (5,6) provides a controlled environment to simulate the ascent of a humid parcel of polluted air in the atmosphere. The cloud forms as the pressure and temperature of the moist air decreases. By controlling the physical conditions influencing cloud growth (i.e. initial temperature, relative humidity, cooling rate), and the size, composition, and concentration of suspended particles, chemical transformation rates of gases and particles to dissolved ions in the cloud water can be measured. These rates can be compared with those derived from physical/chemical models (7,9) which involve variables such as liquid water content, solute concentration, the gas/liquid interface, mass transfer, chemical equilibrium, temperature, and pressure. 

A functional representation of the cloud chemistry simulated chamber is shown in Figure 1. The chamber is constructed of a cylindrical aluminum inner shell 1.8 m in diameter, 2.5 m in height with dome-shaped ends that provide a total volume of 6.6 m. The... 

The cloud chemistry simulation chamber is a complicated measurement system which cannot be totally controlled, and it is necessary to... 

The claim by G A that only one of these traditions developed techniques to imitate real-world conditions is quite misleading. Both traditions used the cloud chamber to manufacture an artificial environment that approximates known phenomena. For the Cavendish physicists, the cloud chamber became one of the defining instruments of particle physics, precisely because the laboratory phenomena were modeled on the movement of the charged particles. The knotty clouds blended into the tracks of alpha particles and the threadlike" clouds simulate beta-particle trajectories (Galison Assmus, 1989, p. 268). Of course, G A are correct that these physicists aspired to dissect nature into its fundamental components, reflecting the long tradition of the corpuscular conception of matter. 

Wang, J., Doussin, J.F., Perrier, S., Perraudin, E., Katrib, Y., Pangui, E., Picquet-Varrault, B. Design of a new multi-phase experimental simulation chamber for atmospheric photosmog, aerosol and cloud chemistry research. Atmos. Meas. Tech. 4, 2465-2494 (2011)... 

Chamber Simulations of Cloud Chemistry The AIDA Chamber... 

Point data was collected at 45 different locations along the 297 m route from the shaft station to the Sub Vertical Rock winder chamber. This produced 42 Gb of 3D point cloud. Horizontal cross sections were taken at 0.5 m 1 m above the tracks. This acquired data then produced a 3D document where the horizontal and vertical cross sections were marked and the rail tracks position superimposed onto. This created a 3D view with all the cross sections and importing all obstructions whether natural or man-made. The various pipes, cables and other obstacles are clearly visible when the simulation is run. 

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