Clouds water

One such feedback is the influence of clouds and water vapor. As the climate warms, more water vapor enters the atmosphere. But how much And which parts of the atmosphere, high or low And how does the increased humidity affect cloud formation While the relationships among clouds, water vapor, and global climate are complicated in and of themselves, the situation is further complicated by the fact that aerosols exert a poorly understood influence on clouds. 

Galloway, J.N. Likens, G.E. Hawley, M.E. Science, 1984,226, pp 829-831. Castillo, R. An Investigation of the Acidity of Stratus Cloud Water and Its Relationship to Droplet Distribution, pH of Rain and Weather Parameters, Ph.D. Thesis, Dept. Atmos. Sci., State University of New York, Albaity, NY, 1979. 

Anthropogenic Modifications of the Acid-Base Balance of Rainwater Alkalinity in Cloud Water "Acid Rain"... 

Fig. 16-4 pH sensitivity to SO4- and NH4. Model calculations of expected pH of cloud water or rainwater for cloud liquid water content of 0.5 g/m. 100 pptv SO2, 330 ppmv CO2, and NO3. The abscissa shows the assumed input of aerosol sulfate in fig/m and the ordinate shows the calculated equilibrium pH. Each line corresponds to the indicated amoimt of total NH3 + NH4 in imits of fig/m of cloudy air. Solid lines are at 278 K, dashed ones are at 298 K. The familiar shape of titration curves is evident, with a steep drop in pH as the anion concentration increases due to increased input of H2SO4. (From Charlson, R. J., C. H. Twohy and P. K. Quinn, Physical Influences of Altitude on the Chemical Properties of Clouds and of Water Deposited from the Atmosphere." NATO Advanced Research Workshop Acid Deposition Processes at High Elevation Sites, Sept. 1986. Edinburgh, Scotland.)... 

The total wet deposition flux consists of 2 contributory factors. The first derives from the continuous transfer of Hg to cloud water, described by chemistry models. There are 2 limiting factors 1) the uptake of gas phase Hg(0), which is regulated by the Hemy s corrstant and 2) the subsequent oxidation of Hg(0) to Hg(ll), which is governed by reaction rate constants and the irritial concentratiorrs of the oxidant species. The total flirx depends on the hquid water content of the cloud and the percentage of the droplets in the cloud that reach the Earth s surface. 

A TKISolver model called RAINDROP.TK has beendeveloped to incorporate the full Charlson-Vong model of cloud water equilibrium Q2), including the temperature dependence of all equilibrium constants. The iterative solver makes it possible to compute the pH at charge neutrality without having to make plots of intermediate results. The Rule Sheet is shown in Figure 3. 

The following problem, taken to match the conditions in Figure 2 of reference 13, is typical of those solved in less than one minute on an IBM PC with this model "a cloud at 278 K contains 0.5 grams of liquid water per cubic meter of air. The atmo here of the cloud contains 5 ppb sulfur dioxide, 340 ppm carbon dioxide, 0.29 jig/m of nitrogen base, 3 xg/m of sulfate aerosol, and no nitrate aerosol. What is the pH of the cloud water Figure 4 shows the Variable Sheet after solution. 

The last of the Miletus philosophers was Anaximenes. His dates are also uncertain, but he must have created his theory before 494 B.C. when the Persians destroyed Miletus. Apparently Anaximenes did not find Anaximander s ideas very convincing, because he maintained that the fundamental element was air. Anaximenes maintained that fire was rarefied air and that air could be condensed into all known substances. Progressive condensations successively condensed it into wind, clouds, water, and finally into earth and stone. Just as our soul being air, holds us together, he said, so do breath and air encompass the whole world. ... 

Imamura, T., Y. Rudich, R. K. Talukdar, R. W. Fox, and A. R. Ravishankara, Uptake of NO, on Water Solutions Rate Coefficients for Reaction with Cloud Water Constituents, . /. Phys. Chem., 101, 2316-2322 (1997). 

The equilibria discussed earlier apply to S02 dissolved in pure water, and these have commonly been used for calculations of the concentrations of S(IV) in atmospheric droplets. However, a variety of measurements of the concentration of S(IV) in fog and cloud-water show that these concentrations are far in excess of what is expected based only on equilibria. Water droplets in the atmosphere, especially in or near urban areas, do not consist of pure water they contain species such as aldehydes and Fe3+ that are known to form complexes in solution with the bisulfite or sulfite ions. 

Anastasio, C., B. C. Faust, and J. M. Allen, Aqueous Phase Photochemical Formation of Hydrogen Peroxide in Authentic Cloud Waters, J. Geophys. Res., 99, 8231-8248 (1994). 

Mitchell, North Carolina, Air Waste, 43, 1074-1083 (1993). Arakaki, T., C. Anastasio, P. G. Shu, and B. C. Faust, Aqueous-Phase Photoproduction of Hydrogen Peroxide in Authentic Cloud Waters Wavelength Dependence, and the Effects of Filtration and Freeze-Thaw Cycles, Atmos. Environ., 29, 1697-1703 (1995). Arakaki, T., and B. C. Faust, Sources, Sinks, and Mechanisms of Hydroxyl Radical ( OH) Photoproduction and Consumption in Authentic Acidic Continental Cloud Waters from Whiteface Mountain, New York The Role of the Fe(r) (r = II, III) Photochemical Cycle, . /. Geophys. Res., 103, 3487-3504 (1998). Atkinson, R., D. L. Baulch, R. A. Cox, R. F. Hampson, Jr., J. A. Kerr, M. J. Rossi, and J. Troe, Evaluated Kinetic and Photochemical... 

Gaseous hydrogen peroxide is a key component and product of the earth s lower atmospheric photochemical reactions, in both clean and polluted atmospheres. Atmospheric hydrogen peroxide is believed to be generated exclusively by gas-phase photochemical reactions (lARC, 1985). Low concentrations of hydrogen peroxide have been measured in the gas-phase and in cloud water in the United States (United States National Library of Medicine, 1998). It has been found in rain and surface water, in human and plant tissues, in foods and beverages and in bacteria (lARC, 1985). 

Figure 16.1 Ranges of steady-state concentrations of reactive oxygen species in sunlit surface waters (sw), sunlit cloud waters (cw), drinking-water treatment (dw), and the troposphere (trop(g)). Data from Sulzberger et al. (1997) and Atkinson et al. (1999).

Cloud Water and Precipitation Collectors. Several methods have been developed for collecting cloud water samples (24-26). Probably the device most commonly used in warm clouds is the slotted rod collector developed by the Atmospheric Science Research Center at the State University of New York (SUNY) at Albany. Commonly known as the ASRC collector (25), this collector consists of an array of rods constructed from Delrin (a form of nylon). Each rod is hollow and has a slot located at its forward stagnation line. The rod radius determines the collection efficiency as a function of particle size, the rods are sized to collect cloud droplets but not submicrometer aerosol particles, and the 50% cutoff is calculated to be at about 3 xm. 

Mounting of the cloud water collectors on the aircraft is a critical issue because flow-field effects can easily distort the size distribution of drops. If at all possible, the collector should be mounted on a pylon so that the collector is in the free airstream. Substantially greater efficiencies can be achieved if the collector is mounted with a forward inclination of about 12° to 15° relative to a perpendicular from the aircraft longitudinal centerline. This kind of mounting accounts for the nose-up attitude at which most aircraft fly under cruise conditions and also provides a component of the airstream to drive impacted cloud droplets down the rod into the collection vessel, minimizing losses due to blow-off (28). 

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