Download or read book A Cloud Chamber Study of the Effect Which Nonprecipitating Clouds Have on the Aerosol Size Distribution written by and published by . This book was released on 1992 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: When an air parcel in the atmosphere passes through a nonprecipitating cloud cycle, a subset of the aerosol population called cloud condensation nuclei (CCN) is activated and forms cloud droplets. During the cloud phase, trace gases, such as SO2, are dissolved into the droplets and undergo aqueous-phase chemical reactions, forming low-volatility products, such as sulfates, which remain as residue when the cloud droplets evaporate. The resulting increase in residual mass can have a dramatic effect on the aerosol size distribution, causing the CCN to grow relative to the smaller particles (interstitial aerosol) which were not activated in the cloud. This process was graphically demonstrated in a series of experiments carried out in the Calspan 600 m3 environmental chamber, under conditions where the precloud reactants could be carefully controlled. Size distributions taken before and after a cloud cycle showed significant conversion of SO2 to H2SO4 and a dramatic change in the aerosol size distribution. Subsequent cloud cycles (with the same expansion rate and trace gas concentrations) exhibited very small mass conversion rates. The decreased conversion rate is explained by the increased acidity of the cloud droplet due to the increased mass of the CCN. The terminal size of the resulting CCN was on the order of one-fiftieth the size of the cloud droplets. The pH of a droplet formed on a sulfuric acid aerosol particle one-fiftieth its size is about 5. Atmospheric aerosols, Atmospheric chemistry.
Download or read book Global Atmospheric Change and its Impact on Regional Air Quality written by Ian Barnes and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NATO ARW in Irkutsk was an excellent occasion for the coming together of Eastern and Western scientists who are involved in tropospheric science; the workshop has greatly contributed to the scientific and social understanding among the participants from the many different countries. Many new personal contacts were made which will help to strengthen future collaborations. In particular, the Lake Baikal area and the Limnological Institute offer splendid opportunities for environmental research which, in part, is already on going. For most participants it was the first time to see the impressive nature of the Lake Baikal region. Hopefully, there will be a chance for a follow-up event in Siberia where researchers from the East and West can again meet and engage in fruitful scientific dialogue. The book contains extended abstracts of the lectures and the poster presentations presented at the NATO ARW "Global Atmospheric Change and its Impact on Regional Air Quality" Irkutsk, Lake Baikal, Russian Federation, August 21-27, 2001. The ARW was composed of 22 oral presentations by key lecturers and 6 additional shorter oral presentations from participants. In a special poster session the 36 poster contributions were presented and discussed. Unfortunately not all contributors submitted extended abstracts, however, to compensate two contributions have been added from 2 participants who were originally invited but were unable to attend.
Download or read book Acid Precipitation written by and published by . This book was released on 1993 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerosol Pollution Impact on Precipitation written by Zev Levin and published by Springer Science & Business Media. This book was released on 2008-09-30 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: Life on Earth is critically dependent upon the continuous cycling of water between oceans, continents and the atmosphere. Precipitation (including rain, snow, and hail) is the primary mechanism for transporting water from the atmosphere back to the Earth’s surface. It is also the key physical process that links aspects of climate, weather, and the global hydrological cycle. Changes in precipitation regimes and the frequency of extreme weather events, such as floods, droughts, severe ice/snow storms, monsoon fluctuations and hurricanes are of great potential importance to life on the planet. One of the factors that could contribute to precipitation modification is aerosol pollution from various sources such as urban air pollution and biomass burning. Natural and anthropogenic changes in atmospheric aerosols might have important implications for precipitation by influencing the hydrological cycle, which in turn could feed back to climate changes. From an Earth Science perspective, a key question is how changes expected in climate will translate into changes in the hydrological cycle, and what trends may be expected in the future. We require a much better understanding and hence predictive capability of the moisture and energy storages and exchanges among the Earth’s atmosphere, oceans, continents and biological systems. This book is a review of our knowledge of the relationship between aerosols and precipitation reaching the Earth's surface and it includes a list of recommendations that could help to advance our knowledge in this area.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1966 with total page 1492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Practical Guide to Atmospheric Simulation Chambers written by Jean-François Doussin and published by Springer Nature. This book was released on 2023-05-25 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access title presents atmospheric simulation chambers as effective tools for atmospheric chemistry research. State-of-the-art simulation chambers provide unprecedented opportunities for atmospheric scientists to perform experiments that address the most important questions in air quality and climate research. The book covers technical details about chamber preparation and practical guidelines on their usage, while also delivering relevant historical and contextual information. It not only serves as a key publication for knowledge transfer within the simulation chamber research community, but it also provides the global atmospheric science community with a unique resource that outlines best practice for the operation of simulation chambers. The authors summarize the latest advances in chamber interoperability and standard protocols in order to provide the research community and the next generations of scientists with a unique technical reference guide for the use of simulation chambers. The volume will be of great interest to researchers and graduates working in the fields of Atmospheric and Environmental Sciences.
Download or read book Aerosol Cloud Interactions in Turbulent Clouds written by and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : The influence of aerosol concentration on the cloud droplet size distribution is investigated in a laboratory chamber that enables turbulent cloud formation through moist convection. In chapter 2, moist Rayleigh-Bénard convection with water saturated boundaries is explored using a one-dimensional-turbulence model. This study provides some background about supersaturation statistics in moist convection. Chapters 3 - 7 discuss the experimental and theoretical investigation of aerosol-cloud interactions and cloud droplet size-distributions in turbulent conditions. The experiments are performed in a way so that steady-state microphysics are achieved, with aerosol input balanced by cloud droplet growth and fallout. As aerosol concentration is increased the cloud droplet mean diameter decreases as expected, but the width of the size distribution is also observed to decrease sharply. The aerosol input allows for cloud generation in the limiting regimes of fast microphysics (tctt) for high aerosol concentration, and slow microphysics (tctt)for low aerosol concentration; here, tc is the phase relaxation time and tt is the turbulence correlation time. The increase in the width of the droplet size distribution for the low aerosol limit is consistent with the larger variability of supersaturation due to the slow microphysical response. A stochastic theory developed based on the Langevin equation for supersaturation predicts that the standard deviation of the squared droplet radius should increase linearly with a system time scale defined as ts-1 = tc-1 + tt-1, and the measurements are in excellent agreement with this finding. These experiments are discussed in chapters 3 and 4. This effect of varying cloud dropletsize-distributionwidth underscores the importance of droplet size dispersion for aerosol indirect effects. An application of this coupling of aerosol and supersaturation fluctuations during the 'cloud-cleansing' process is discussed in chapter 5. Cloud droplet relative dispersion, defined as the standard deviation over the mean cloud droplet size (d = sigmar / r ), is of central importance in determining and understanding aerosol indirect effects. The analytical expression of d obtained from the stochastic theory is found to depend on the cloud droplet removal time, which in turn increases with the cloud droplet number density. The results show that relative dispersion decreases monotonically with increasing droplet number density, consistent with some recent atmospheric observations. The albedo susceptibility due to turbulence broadening has the same sign as the Twomey effect and augments it by order 10%. These results, along with the test of a commonly-used effective radius parameterization, are presented in chapter 6.), is of central importance in determining and understanding aerosol indirect effects. The analytical expression of d obtained from the stochastic theory is found to depend on the cloud droplet removal time, which in turn increases with the cloud droplet number density. The results show that relative dispersion decreases monotonically with increasing droplet number density, consistent with some recent atmospheric observations. The albedo susceptibility due to turbulence broadening has the same sign as the Twomey effect and augments it by order 10%. These results, along with the test of a commonly-used effective radius parameterization, are presented in chapter 6. In chapter 7, theoretical expressions for cloud droplet size-distribution shape are evaluated using measurements from controlled experiments in the Pi-Chamber. Three theoretical distributions obtained from a Langevin drift-diffusion approach to stochastic condensation are tested. Statistical techniques of ꭕ2 test, sum of squared errors of prediction, and residual analysis are employed to judge relative success or failure of the theoretical distributions to describe the experimental data. In relative comparison, the most favorable comparison to the measurements is the expression for stochastic condensation with size-dependent droplet removal rate.
Download or read book Aerosol Forcing of Climate written by R. J. Charlson and published by . This book was released on 1995-08-24 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global climate change as a consequence of anthropogenic changes in the chemical composition of the atmosphere poses scientific questions of a nature and interdisciplinary scope that are unprecedented. Uncertainties in the climate forecast are large and thus far have hampered the establishment of a clear world plan for preventing or mitigating against unacceptable effects. The forecast of global and regional climate changes depends upon the development of a sound understanding of the factors that change the global heat balance and thus influence the climate. Changes in heat balance due to anthropogenic or externally imposed changes in the chemical composition of the atmosphere are referred to as forcings. While the uncertainties in the global mean greenhouse-gas forcing are not negligible (??? 15%), uncertainties in forcings by changes in the atmospheric aerosol and in clouds are much larger, and in some cases even include uncertainty in the sign of the forcing. Reductionist science, with its compartmentalized disciplines, has not coped effectively with the scientific problems of aerosols and their effects, largely because of a need for simultaneous consideration of chemical processes, chemical properties, physical properties, and a wide variety of physical processes and consequences. In the case of natural aerosols and their effects on clouds, it is even necessary to include studies of microbiology and of biochemistry. This volume ? the record of intense, interdisciplinary debate between atmospheric chemists, meteorologists, physicists, and biogeochemists - considers the subset of climate forcings due to atmospheric aerosols, with particular emphasis on integrating the necessary disciplinary components. It is truly unique in its interdisciplinary approach. The information contained in the overview papers and summary reports will be of interest to policymakers and scientists alike. Goal of this Dahlem Workshop to assess the controlling factors, geographic and temporal variations of the radiative properties of atmospheric aerosols, and to examine the extent to which their forcing through direct and indirect effects counteracts greenhouse-gas forcing on regional and global climate.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 1684 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preliminary Investigation of the Role that DMS Dimethyl Sulfide and Cloud Cycles Play in the Formation of the Aerosol Size Distribution written by W. A. Hoppel and published by . This book was released on 1987 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of experiments designed to study the production of new particulate matter by photolysis of dimethyl sulfide (DMS) and the effect that nonprecipitating clouds, have on the aerosol size distributions were carried out in Calspan Corporation's 600 cum environmental chamber during January and February 1986. The results show that DMS, the most abundant natural source of sulfur, is photooxidized to some product of low volatility that can form new particles by homogeneous nucleation or condense on existing aerosols causing them to grow. To explain these observations, a theoretical study of the nucleation properties of methane sulfonic acid (MSA) was undertaken. The nucleation thresholds, calculated using thermodynamic data for MSA, show that at 70% RH, and MSA concentration of only 0.006 ppb will result in a supersaturated environment in which MSA will condense on preexisting particles larger than 0.02 micron radius. If the MSA concentrations increase to 30 ppb, then spontaneous formation of MSA solution droplets occurs by homogeneous binary nucleation. Simulations of the evolution of the size distribution observed for the DMS irradiation experiments with a dynamic aerosol model that includes the effects of coagulation, growth by condensation, and deposition to the walls of the chamber, yield results that are in excellent agreement with the observed evolution.
Download or read book Air Pollution written by and published by . This book was released on 1999 with total page 1120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1993 with total page 1832 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book IGACtivities Newsletter written by International Global Atmospheric Chemistry (IGAC) Project and published by . This book was released on with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Representing Droplet Size Distribution and Cloud Processes in Aerosol cloud climate Interaction Studies written by Wei-Chun Hsieh and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The indirect effect of aerosols expresses how changes in aerosols would influence clouds and cause impacts on Earth's climate and hydrological cycle. The current assessment of the interactions between aerosols and clouds is uncertain and parameterizations used to represent cloud processes are not well constrained. This thesis first evaluates a cloud activation parameterization by investigating cloud droplet number concentration closure for stratocumulus clouds sampled during the 2005 MArine Stratus Experiment (MASE). Further analysis of the droplet size distribution characteristics using the extended parameterization is performed by comparing the predicted droplet spectra with the observed ones. The effect of dynamical variability on the droplet size distribution evolution is also investigated by considering a probability density function for updraft velocity. The cumulus and stratocumulus cloud datasets from in-situ field measurements of NASA's Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) and Coastal STRatocumulus Imposed Perturbation Experiment (CSTRIPE) campaigns are used for this task. Using the same datasets, the autoconversion rate is calculated based on direct integration of kinematic collection equation (KCE). Six autoconversion parameterizations are evaluated and the effect of turbulence on magnifying collection process is also considered. Finally, a general circulation model (GCM) is used for studying the effect of different autoconversion parameterizations on indirect forcing estimates. The autoconversion rate given by direct KCE integration is also included by implementing a look-up table for collection kernels. Although these studies add more variability to the current estimate of aerosol indirect forcing, they also provide direction towards a more accurate assessment for climate prediction.
Download or read book The Principles of Cloud Chamber Technique written by J. G. Wilson and published by Cambridge University Press. This book was released on 2014-06-12 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Originally published in 1951, this book examines the potential of the cloud chamber as an instrument of precise measurement.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1993-02 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt:
