Download or read book Laboratory Studies of Ice Formation Via Deposition Mode Nucleation Onto Mineral Dust and N hexane Soot Samples written by Zaminhussein Abdulali Kanji and published by . This book was released on 2006 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laboratory studies are described whereby the heterogeneous ice nucleating ability of various dust samples was studied for particles mounted on a hydrophobic cold stage. Ice formation is observed using digital photography. The relative humidity with respect to ice (RHIce) and temperature conditions of the flow system are validated by observing (NH4)2SO 4 deliquescence. Four types of solid mineral samples, including authentic Saharan dust, and commercial samples of alumina, silica and montmorillonite, were investigated in the deposition freezing mode. The size of the dust particles ranged from 0.5 to 5 microns, and the temperature range was from 263 to 218 K. With roughly 104 particles present on the cold stage, the onset for ice formation was observed at low relative humidities, between 102 and 108% RHIce, for all samples and temperatures. This indicates that deposition mode nucleation is an efficient mode of ice formation, particularly under the cold temperatures prevalent in the cirrus regime. By contrast, ice deposition onto n-hexane soot particles was not nearly so efficient. Nucleation rates prevalent in the experiment are calculated as a function of relative humidity from a suite of experiments conducted with Saharan dust where the dependence of the onset RHIce as a function of the total dust surface area was measured.
Download or read book Laboratory Studies of Deposition Mode Heterogeneous Ice Nucleation written by Zaminhussein Abdulali Kanji and published by . This book was released on 2009 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: The indirect aerosol effect contributes to major uncertainties in determining the radiation budget of the earth. A large uncertainty is due to the formation of ice clouds onto natural or anthropogenic aerosols. Field studies have shown that mineral type particles are often associated with ice crystals in the mid-upper troposphere and given the long residence time in the atmosphere of dust particles (∼2 weeks in the absence of precipitation), their contribution to ice formation processes is not fully defined.It was concluded that there is no single value for the onset of ice formation in the atmosphere via deposition freezing. The associated contact angles show that there is a distribution of active sites on IN and that not all active sites have the same affinity for initiation of ice formation even within the same aerosol type. This work provides evidence that deposition mode nucleation can be an alternate pathway to homogeneous nucleation when mineral aerosols are present in the troposphere since the high T-low RH conditions required for deposition mode nucleation are more easily encountered in the atmosphere than the low T-high RH required for homogeneous nucleation.In order to probe ice formation onto natural mineral dust in a setting where it could be suspended as aerosol, a new continuous flow diffusion chamber (CFDC) was built. This allowed investigations of the effects of total aerosol surface area and particle size. The CFDC was also used in an international inter-comparison of ice nucleation instrumentation to compare efficiencies of soot, biological aerosol (bacteria) and samples of natural desert dusts from different regions of the world. The laboratory observations were parameterized using nucleation rates (Jhet) and contact angles (theta) as described by classical nucleation theory.For both this experimental technique and a static one developed during the candidate's Masters degree, mineral dust particulate proved to be the most efficient ice nuclei (IN) activating at RH with respect to ice (RH i) as low as 105% at T=233 K. The efficiency varied with particle size and aerosol surface area (SA). Large particles or higher SA activated at lower RHi than small particles or lower SA. The static chamber was sensitive to the first ice event out of a large SA and therefore gave true onset RHi, which was lower than the onset defined by the CFDC studies, which was not sensitive to a single ice event. In addition the static chamber used a broader size range of particulate matter, including super micron particles while the CFDC particles sizes were restricted to below 0.5 microm. Soot and organic coated dust particles were inefficient IN compared to pure dust. Soot aerosols showed some efficiency at T
Download or read book Nucleation of Water written by Ari Laaksonen and published by Elsevier. This book was released on 2021-11-25 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nucleation of Water: From Fundamental Science to Atmospheric and Additional Applications provides a comprehensive accounting of the current state-of-the-art regarding the nucleation of water. It covers vapor-liquid, liquid-vapor, liquid-ice and vapor-ice transitions and describes basic kinetic and thermodynamic concepts in a manner understandable to researchers working on specific applications. The main focus of the book lies in atmospheric phenomena, but it also describes engineering and biological applications. Bubble nucleation, although not of major atmospheric relevance, is included for completeness. This book presents a single, go-to resource that will help readers understand the breadth and depth of nucleation, both in theory and in real-world examples. Offers a single, comprehensive work on water nucleation, including cutting- edge research on ice, cloud and bubble nucleation Written primarily for atmospheric scientists, but it also presents the theories in such a way that researchers in other disciplines will find it useful Written by one of the world’s foremost experts on ice nucleation
Download or read book Supercooling written by Peter Wilson and published by BoD – Books on Demand. This book was released on 2012-03-09 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercooled liquids are found in the atmosphere, in cold hardy organisms, in metallurgy, and in many industrial systems today. Stabilizing the metastable, supercooled state, or encouraging the associated process of nucleation have both been the subject of scientific interest for several hundred years. This book is an invaluable starting point for researchers interested in the supercooling of water and aqueous solutions in biology and industry. The book also deals with modeling and the formation subsequent dendritic growth of supercooled solutions, as well as glass transitions and interface stability.
Download or read book An Introduction to Clouds written by Ulrike Lohmann and published by Cambridge University Press. This book was released on 2016-06-23 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a fundamental understanding of clouds, from microphysics to climate, with supplementary problem sets and questions.
Download or read book Experimental Studies on Deposition and Immersion Mode Ice Nucleation on Mineral Dust written by André Welti and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface Property Impacts on Heterogeneous Ice Nucleation of Engineered Materials written by Katherine Marak and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particles can facilitate heterogenous ice formation in the troposphere and stratosphere by acting as ice nuclei, modulating cloud formation/dissipation, precipitation, and their microphysical properties. Heterogeneous ice nucleation is driven by ice embryo formation on the particle surface, which can be influenced by features of the surface such as crystallinity, surface structure, lattice structure, defects, and functional groups. Probing for deeper understanding of what surface features have the greatest impact on heterogeneous freezing is significant and can be done with synthetic and modified materials. To characterize the effect of crystallinity, pores, and surface functional groups towards ice nucleation, samples of comparable silica systems, specifically, quartz, ordered and non-ordered porous amorphous silica samples with a range of pore sizes (2-11 nm), and non-porous functionalized silica spheres were used as models for mineral dust aerosol particles (Chapter 2). The results suggest that crystallinity has a larger effect than porosity on ice nucleation activity, as all of the porous silica samples investigated had lower onset freezing temperatures and lower ice nucleation activities than quartz. Our findings also suggest that pores alone are not sufficient to serve as effective active sites, and need some additional chemical or physical property, like crystallinity, to nucleate ice in immersion mode freezing. The addition of a low density of organic functional groups to non-porous samples showed little enhancement compared to the inherent nucleation activity of silica with native surface hydroxyl groups. The density of functional groups investigated in this work suggests that a different arrangement of surface groups may be needed for enhanced immersion mode ice nucleation activity. In summary, crystallinity dictates the ice nucleation activity of silica samples rather than porosity or low-density surface functional groups. Silver and gold nanoparticles with thiol ligands of different functionalities (alkane, carboxylic acid and alcohol) were investigated for immersion ice nucleation activities (Chapter 3). The alcohol ligand nanoparticles of both silver and gold had significantly higher activities than the alkane thiol ligand, with a 4.5 oC and 10.7 oC difference in median freezing temperature respectively. Silver nanoparticles capped with thiol alcohol ligands were also tested for aggregation and oxidative stability. The silver nanoparticles are oxidatively stable for at least 2 years. We have also shown that aggregates of nanoparticles have likely caused the activity for all of the silver and gold samples, as ice nucleation activity strongly diminished when large aggregates (>200 nm) were filtered from solution. Investigating the ice nucleation activity of synthetic ZSM-5 samples with varying Si:Al helps to clarify ice nucleation activity of natural mineral dust samples, which are often aluminosilicate based materials (Chapter 4). Additionally, ammonium is a very common cation in the atmosphere, and its effects on ice nucleation activity are still being studied. Ice nucleation temperature increases with increasing Al content. Additionally, when ammonium is the cation that is strongly adsorbed to the surface and in pores, initial freezing temperatures are reduced by up to 6 oC. Seeing a drastic decrease in ice nucleation activity in the presence of ammonium, suggests that the cation can interact with the surface to block active sites. In addition to ice nucleation, dust samples can affect human health. The goal of Chapter 5 is to present risk assessments for trace element concentrations in PM10 dusts from simulated road material and township roads with/without oil and gas produced water brine (O&GPWB) treatment. PM10 trace metal quantification was conducted by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and compared to values from EDS analysis on PM2.5. Among adults, PM10 inhalation lifetime cancer risks (CRinh range: 2.39E+01 to 7.73E+01) and hazard quotients for As, Ni and Pb exposure were elevated for O&GPWB, SFSR and RRA. Cumulative Pb dose for the O&GPWB-treated roads was 71 ng/kg by age 21, compared with 37 ng/kg for non-treated roads. Our results may be consistent with elevated blood lead (Pb) concentrations above state averages in this rural O&G producing region.
Download or read book Laboratory Studies of Deposition Mode Heterogeneous Ice Nucleation Effect of Ice Nuclei Composition Size and Surface Area written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: PhD.
Download or read book Investigation of Ice Nucleation Properties Onto Soot Bioaerosol and Mineral Dust During Different Measurement Campaigns written by Cédric Chou and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Modeling Study of Heterogeneous Ice Nucleation on Mineral Aerosol Particles and Its Impact on a Convective Cloud written by Thibault Hiron and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Characterization of Heterogeneous Ice Nuclei in the Atmosphere written by Sarah Sihvonen and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particles impact the climate by serving as the seeds to form water droplets and ice to form clouds. However, these aerosol-cloud interactions are the least understood aspect of our understanding of the climate system. Mineral dust aerosol is the largest global source of ice nucleating particles. During atmospheric transport, mineral dust can be exposed to sulfuric acid, which has been shown to decrease the ice nucleation activity of these particles. Many explanations for this observation, such as chemical changes to the surface or product formation that blocks active sites, have been suggested. Our research focused on building a molecular picture of these surfaces to understand why sulfuric acid exposure reduces the ice nucleation activity of clay minerals such as kaolinite. We performed studies using X-ray diffraction and solid state NMR that investigate the changes that clay minerals undergo as a result of acid exposure. We are the first to show that the formation of a product on the surface of kaolinite was responsible for the decreased ice nucleation activity, not surface changes to the mineral itself. We continued to study aerosol-cloud interactions by using parcel models that explore the impact of ice growth surface kinetics on the competition between heterogeneous and homogeneous ice nucleation in clouds. We found that impaired growth of ice favors homogeneous freezing. The parcel models will be expanded to include our work on clay minerals to explore the impact of chemical aging of ice nuclei on overall cloud properties. We also studied the effect of acidic-processing on coal fly ash samples. Coal fly ash has been found to have a similar atmospheric impact as mineral dust, but is studied to a lesser extent. Like mineral dust, coal fly ash can serve as a source of bioavailable iron to phytoplankton in nutrient limited regions of the ocean. Fly ash has also been found to serve as an ice nucleating material. We performed aqueous sulfuric acid-treatment on fly ash samples representative of the types produced in the United States. We found that a soluble salt, gypsum (hydrated calcium sulfate), formed on three out of four samples. The most iron rich sample did not react with sulfuric acid. However, acidic-processing was shown to increase the amount of soluble iron which has implications for the biogeochemical cycle. These results also demonstrate that further work investigating these fly ash systems is warranted. In addition to our work on ice nucleation, we constructed a photoacoustic spectrometer to measure the absorbance of aerosol particles to study the optical properties of atmospheric aerosol. These measurements will aid in understanding the interactions of aerosol particles with light and the radiative balance of the planet.
Download or read book Laboratory Studies of Water Ice Nucleation and Growth at Conditions Relevant to Martian Cloud Formation written by Brendan Douglas Mar and published by . This book was released on 2011 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biological Ice Nucleation and Its Applications written by Richard E. Lee and published by American Phytopathological Society. This book was released on 1995 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing from a variety of disciplines, this book includes coverage of frost sensitivity of plants, winter survival of certain insects, screening for food pathogens, and biological control.
Download or read book Ice Nucleation written by James Goold (Jr.) and published by . This book was released on 1968 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heterogeneous Nucleation of Ice on Anthropogenic Organic Particles Collected in Mexico City written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study reports on heterogeneous ice nucleation activity of predominantly organic (or coated with organic material) anthropogenic particles sampled within and around the polluted environment of Mexico City. The onset of heterogeneous ice nucleation was observed as a function of particle temperature (Tp), relative humidity (RH), nucleation mode, and particle chemical composition which is influenced by photochemical atmospheric aging. Particle analyses included computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). In contrast to most laboratory studies employing proxies of organic aerosol, we show that anthropogenic organic particles collected in Mexico City can potentially induce ice nucleation at experimental conditions relevant to cirrus formation. The results suggest a new precedent for the potential impact of organic particles on ice cloud formation and climate.
Download or read book Ice Nucleation on Uncoated and Coated Atmospheric Mineral Dust Particles written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ice Nucleation of Metal Oxides as Model Systems of Atmospheric Aerosol Particles written by Esther Chong and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanism of ice nucleation continues to be an ongoing discussion within the scientific community. The debate centers around two central questions: how an aerosol particle interacts with water and what characteristics of the particle promote ice nucleation. Understanding of aerosol-cloud interactions, whether it is the formation of cloud condensation nuclei or ice nuclei, has been a source of some of the highest uncertainty in determining the radiative budget of the Earth. The complexity of atmospheric aerosol particles makes it difficult to decide on which particular characteristics on a particle affects its ice nucleation activity. To study specific features, we used model metal oxide systems to control as many variables as possible. By systematically determining which properties and to what extent they affect ice nucleation, we may extrapolate the mechanism of ice nucleation and decrease the uncertainty around aerosol-cloud interactions. The metal oxide systems included aluminum, iron, titanium, and manganese oxide, which are all found as components in mineral dust. As one of the most prevalent ice nucleating particles in the atmosphere, mineral dust is an ideal atmospheric particle for us to simulate with our model systems. A combination of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were used to characterize our model systems. The aluminum oxides were chosen to study the effect of crystallinity and lattice matching on ice nucleation. The three most crystalline samples, corundum [[alpha]-Al2O3], gibbsite [Al(OH)3], and bayerite [Al(OH)3], were also found to have the highest ice nucleation activity. Then, calculations of the lattice match of the aluminum oxides with respect to hexagonal ice found that the best ice nucleating particle was corundum [[alpha]-Al2O3], which had the highest lattice match along the a- and b-axis. Therefore, a combination of high crystallinity and high lattice match with hexagonal ice correlated with a high ice nucleation activity. Then, iron oxides were studied to expand further on the aluminum oxide system by exploring if the lattice match is a viable property to determine ice nucleation activity despite the difference in composition. Overall, wüstite [FeO] had a high lattice match and the highest ice nucleation activity among the iron oxide samples. Because wüstite [FeO] was milled for the ice nucleation experiments, the effect of milling on ice nucleation was also studied. By comparing milled and 20 [mu]m sieved of both wüstite [FeO] and MnO, we saw that physical defects formed by the mill had minimal improvements on the ice nucleation activity of MnO. XPS showed that milled wüstite [FeO] had more exposed hydroxyls at the surface compared to the sieved wüstite [FeO]. In contrast, milled and sieved MnO showed similar concentrations of oxygen and hydroxyl species. Thus, the high lattice match and the exposure of hydroxyl groups after milling were the leading factors to wüstite [FeO]'s high ice nucleation activity. The last two systems, titanium and manganese oxide, were chosen to confirm that the lattice match trend could be applied to a variety of particles. For the titanium oxides, Ti2O3 was the best ice nucleating particle, but the lattice match was not high. We hypothesize that the dissociation and adsorption of water at the surface of titanium oxides could affect their ice nucleation. The manganese oxides followed the lattice match trend. MnO had the highest ice nucleation activity and the highest lattice match. Thus, the data compilation of all four metal oxides found that a high lattice match with hexagonal ice has a reasonably strong correlation with the immersion ice nucleation activity. The commonality of the lattice match trend between these metal oxide systems has implications of more properties that are good indicators for the ice nucleation activity over a wide range of compounds. If enough of these properties are identified, then it would be possible for cloud models better to predict the ice nucleation activity of complex atmospheric particles and decrease the uncertainty of aerosol-cloud interactions.
