On the Particles in Fogs and Clouds

1893 ◽  
Vol 19 ◽  
pp. 260-263
Author(s):  
John Aitken
Keyword(s):  
Vapour Pressure ◽  
Dust Particles ◽  
Strong Wind ◽  
Great Care ◽  
Rapid Cooling ◽  
Particle Counter ◽  
Large Curvature ◽  
Small Water ◽  
Made In ◽  
Number Of Particles

At the beginning of the paper some observations made on the water particles in clouds on the Rigi on the 21st of May last are described. Previous observations with the fog-particle counter had shown that there is a relation between the density of a cloud and the number of water particles observed. On the occasion above referred to the number was very much greater than corresponded with the density. It is pointed out that the number of dust particles in the air which become centres of condensation depends on the rate at which the condensation is taking place, quick condensation causing a large number of particles to become active, slow condensation causing a small number; and that after the condensation has ceased a process of differentiation takes place, the larger particles, robbing the smaller ones of their water, owing to the vapour-pressure at the surface of drops of large curvature being less than at the surface of drops of smaller curvature. The particles in a cloud are by this process reduced in number, those remaining becoming larger and falling quicker, the cloud thus tending to become thinner by the reduction of the number of particles and by the falling of some of them. It is shown that the exceptional readings above referred to, obtained on the Rigi, were owing to the observations then made being taken in a new and rapidly-formed cloud, due to the strong wind blowing at the time causing a quick ascent and rapid cooling and condensation, the result being the formation of a large number of very small water particles. Though the number was very great, the particles were so small they were only just visible with great care with the magnifying power used in the instrument. Previous observations on cloud particles had been made in slowly-formed or in old clouds after the process of differentiation had been in play for some time, and after the drops had been reduced in number and increased in size.

scholarly journals Quantitative analysis of fine dust particles on moss surfaces under laboratory conditions using the example of Brachythecium rutabulum

2021 ◽  
Author(s):  
Bilitis Désirée Vanicela ◽  
Martin Nebel ◽  
Marielle Stephan ◽  
Christoph Riethmüller ◽  
Götz Theo Gresser
Keyword(s):  
Fine Fraction ◽  
Model Organism ◽  
Dust Particles ◽  
Quantitative Detection ◽  
Suitable Model ◽  
Fine Dust ◽  
Sem Images ◽  
Moss Species ◽  
Laboratory Conditions ◽  
Number Of Particles

AbstractThe identification of a model organism for investigations of fine dust deposits on moss leaflets was presented. An optical method with SEM enabled the quantitative detection of fine dust particles in two orders of magnitude. Selection criteria were developed with which further moss species can be identified in order to quantify the number of fine dust particles on moss surfaces using the presented method. Among the five moss species examined, B. rutabulum had proven to be the most suitable model organism for the method presented here. The number of fine dust particles on the moss surface of B. rutabulum was documented during 4 weeks of cultivation in the laboratory using SEM images and a counting method. The fine dust particles were recorded in the order of 10 μm–0.3 μm, divided into two size classes and counted. Under laboratory conditions, the number of particles of the fine fraction 2.4 μm–0.3 μm decreased significantly.

scholarly journals A Complete and Efficient Multisphere Scattering Theory for Modeling the Optical Properties of Interplanetary Dust

1996 ◽  
Vol 150 ◽  
pp. 419-422 ◽  
Author(s):  
Yu-lin Xu ◽  
Bo Å. S. Gustafson
Keyword(s):  
Light Scattering ◽  
Scattering Theory ◽  
Complete Solution ◽  
Spherical Wave ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Interplanetary Dust Particles ◽  
Scattering Problems ◽  
Long Time ◽  
Made In

For a long time, the dominant scattering theory used in radiative transfer and scattering calculations has been Mie theory, which is the complete solution to the problems of light scattering by single, isotropic, and homogeneous spheres. However, cosmic dust collections show that most of the largest sized interplanetary dust particles may be porous, inhomogeneous, and aggregated and may have quite different scattering properties. Arbitrary configurations of aggregated spheres may provide a reasonable first approximation to realistic light-scattering models of interplanetary dust particles. In the last few decades, progress has been made in developing light scattering theory for interacting spheres, The development of the addition theorems for scalar and vector spherical wave functions (Friedman & Russek, 1954; Stein, 1961; Cruzan, 1962) opened up a new area in the theoretical study of multisphere scattering problems.

scholarly journals THE MEASUREMENT AND DISTRIBUTION OF WOOD DUST

2010 ◽  
Vol 41 (1) ◽  
pp. 25 ◽  
Author(s):  
Andrea Rosario Proto ◽  
Giuseppe Zimbalatti ◽  
Martino Negri
Keyword(s):  
Health And Safety ◽  
Qualitative Assessment ◽  
Dust Particles ◽  
Wood Dust ◽  
High Concentration ◽  
Dust Emissions ◽  
Carcinogenic Agents ◽  
Prevention Model ◽  
Number Of Particles

In Italy, the woodworking industry presents many issues in terms of occupational health and safety. This study on exposure to wood dust could contribute to the realization of a prevention model in order to limit exposure to carcinogenic agents to the worker. The sampling methodology illustrated the analysis of dust emissions from the woodworking machinery in operation throughout the various processing cycles. The quantitative and qualitative assessment of exposure was performed using two different methodologies. The levels of wood dust were determined according to EN indications and sampling was conducted using IOM and Cyclon personal samplers. The qualitative research of wood dust was performed using an advanced laser air particle counter. This allowed the number of particles present to be counted in real time. The results obtained allowed for an accurate assessment of the quality of the dust emitted inside the workplace during the various processing phases. The study highlighted the distribution of air particles within the different size classes, the exact number of both thin and ultra-thin dusts, and confirmed the high concentration of thin dust particles which can be very harmful to humans.

scholarly journals Particle settling and convective mixing in the Saharan Air Layer as seen from an integrated model, lidar, and in-situ perspective

2016 ◽  
Author(s):  
Josef Gasteiger ◽  
Silke Groß ◽  
Bernadett Weinzierl ◽  
Daniel Sauer ◽  
Volker Freudenthaler
Keyword(s):  
Dust Particles ◽  
Depolarization Ratio ◽  
Western Atlantic ◽  
Particle Counter ◽  
Convective Mixing ◽  
Saharan Air Layer ◽  
Lidar Measurements ◽  
Linear Depolarization Ratio ◽  
Aerosol Properties

Abstract. Long-range transport of aerosol in the Saharan Air Layer (SAL) across the Atlantic plays an important role for weather, climate, and ocean fertilization. However, processes occurring within the SAL and their effects on aerosol properties are still unclear. In this work we study particle settling and convective mixing within the SAL based on measured and modeled vertical aerosol profiles in the upper 1 km of the transported SAL. We use ground-based POLIS lidar measurements and airborne particle counter measurements over the Western Atlantic, as well as space-based CALIOP lidar measurements from Africa to the Western Atlantic. In our model we take account of the optical properties and the Stokes gravitational settling of irregularly-shaped Saharan dust particles. We test two hypotheses about the occurrence of convective mixing within the SAL over the Atlantic to explain the aerosol properties observed by the lidars and the particle counter. Our first hypothesis (H1) assumes that no mixing occurs in the SAL leading to an altitude separation of super-micron dust particles as a result of settling. The second hypothesis (H2) assumes that convective mixing occurs in the SAL during the day allowing large super-micron dust particles to stay airborne longer than without convective mixing. In general, a decrease of the particle linear depolarization ratio towards the SAL top is found in the measured lidar data but the decrease is much weaker than modeled in case of H1. The in-situ data on particle number concentrations show a presence of large particles near the SAL top that is inconsistent with H1. Furthermore, the analysis of the CALIOP measurements reveals that the average vertical profile of the linear depolarization ratio of the aerosols in the upper 1 km of the SAL does not change along its transport path over the Atlantic. These findings indicate H2 to be much more likely than H1, giving evidence that convective mixing occurs within the SAL over the Atlantic with significant consequences for the evolution of the size distribution of the super-micron dust particles during transport.

scholarly journals Selective collection of iron-rich dust particles by natural Trichodesmium colonies

2019 ◽  
Vol 14 (1) ◽  
pp. 91-103 ◽  
Author(s):  
Nivi Kessler ◽  
Rachel Armoza-Zvuloni ◽  
Siyuan Wang ◽  
Subhajit Basu ◽  
Peter K. Weber ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
Strong Preference ◽  
Dust Particles ◽  
Gulf Of Aqaba ◽  
Particle Collection ◽  
Free Particles ◽  
Selective Collection ◽  
Number Of Particles

Abstract Dust is an important iron (Fe) source to the ocean, but its utilization by phytoplankton is constrained by rapid sinking and slow dissolution dust-bound iron (dust-Fe). Colonies of the globally important cyanobacterium, Trichodesmium, overcome these constraints by efficient dust capturing and active dust-Fe dissolution. In this study we examined the ability of Trichodesmium colonies to maximize their Fe supply from dust by selectively collecting Fe-rich particles. Testing for selectivity in particle collection, we supplied ~600 individual colonies, collected on multiple days from the Gulf of Aqaba, with natural dust and silica minerals that were either cleaned of or coated with Fe. Using a stereoscope, we counted the number of particles retained by each colony shortly after addition and following 24 h incubation with particles, and documented translocation of particles to the colony core. We observed a strong preference for Fe-rich particles over Fe-free particles in all tested parameters. Moreover, some colonies discarded the Fe-free particles they initially collected. The preferred collection of Fe-rich particles and disposal of Fe-free particles suggest that Trichodesmium can sense Fe and selectively choose Fe-rich dust particles. This ability assists Trichodesmium obtain Fe from dust and facilitate its growth and subsequent contribution to nutrient cycling and productivity in the ocean.

IMPROVING THE EFFICIENCY OF THE VORTEX DUST COLLECTORS

2018 ◽  
Vol 8 (3) ◽  
pp. 39-42
Author(s):  
Svetlana M. PURING ◽  
Denis N. VATUZOV
Keyword(s):  
Energy Consumption ◽  
Venturi Tube ◽  
Dust Particles ◽  
Dust Collector ◽  
Effi Ciency ◽  
Inner Surface ◽  
Separation Chamber ◽  
Secondary Air ◽  
Reducing Energy ◽  
Made In

It is proposed to use a modernized “wet” vortex dust collector for cleaning ventilation emissions from non-adhering dust. The design of the vortex dust collector contributes to its effi ciency by installing irrigation nozzles in the primary and secondary air connections made in the form of a Venturi tube, which allows reducing energy consumption during the cleaning of dusty air. Due to the multidirectional movement of dust particles and splashed water, active coagulation of dust particles and water particles occurs, as well as a liquid fi lm is formed on the inner surface of the separation chamber, which prevents the dust particles from rebounding from the separation chamber and facilitates their collection and washing into a collecting bin.

scholarly journals MADE-IN: a new aerosol microphysics submodel for global simulation of potential atmospheric ice nuclei

2010 ◽  
Vol 3 (4) ◽  
pp. 2221-2290 ◽  
Author(s):  
V. Aquila ◽  
J. Hendricks ◽  
A. Lauer ◽  
N. Riemer ◽  
H. Vogel ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
Ice Crystals ◽  
Dust Particles ◽  
Airborne Measurements ◽  
Cloud Processing ◽  
Ice Nuclei ◽  
Hygroscopic Properties ◽  
Mixing States ◽  
Made In

Abstract. Black carbon (BC) and mineral dust are among the dominant atmospheric ice nuclei, i.e. aerosol particles that can initiate heterogeneous nucleation of ice crystals. When released, most BC and dust particles are externally mixed with other aerosol compounds. Through coagulation with particles containing soluble material and condensation of gases, externally mixed particles may obtain a coating and be transferred into an internal mixture. The mixing state of BC and dust aerosol particles influences their radiative and hygroscopic properties, as well as their ability of building ice crystals. We introduce the new aerosol microphysics submodel MADE-IN, implemented within the ECHAM/MESSy Atmospheric Chemistry global model (EMAC). MADE-IN is able to track separately mass and number concentrations of BC and dust particles in their different mixing states, as well as particles free of BC and dust. MADE-IN describes these three classes of particles through a superposition of seven log-normally distributed modes, and predicts the evolution of their size distribution and chemical composition. Six out of the seven modes are mutually interacting, allowing for the transfer of mass and number among them. Separate modes for the different mixing states of BC and dust particles in EMAC/MADE-IN allow for explicit simulations of the relevant aging processes, i.e. condensation, coagulation and cloud processing. EMAC/MADE-IN has been evaluated with surface and airborne measurements and performs well both in the planetary boundary layer and in the upper troposphere and lowermost stratosphere. Such a model represents a highly appropriate tool for the study of the concentration and composition of potential atmospheric ice nuclei.

scholarly journals III—On the Number of Dust Particles in the Atmosphere of certain Places in Great Britain and on the Continent, with Remarks on the Relation between the Amount of Dust and Meteorological Phenomena

1895 ◽  
Vol 37 (1) ◽  
pp. 17-49 ◽  
Author(s):  
John Aitken
Keyword(s):  
Great Britain ◽  
Dust Particles ◽  
Atmospheric Dust ◽  
Limited Experience ◽  
The Subject ◽  
In The Beginning ◽  
Made In

In a new investigation of this kind it is always desirable to repeat the observations under as many conditions as possible. The variables are so many that with a limited experience it cannot be expected that the subject will be exhausted, or that the conclusions arrived at from early observations will be in all cases confirmed. As an opportunity offered in the beginning of 1890 for repeating the tests made the previous year on the amount of atmospheric dust at different places on the Continent, it seemed desirable that the old ground should be gone over again rather than that the investigation should be extended to new areas. The observations made in this country have also been confined to the same stations as in 1889; and in this paper I intend giving the results of a series of tests repeated at the same stations, at about the same dates, but under the conditions existing in 1890, as has already been given for 1889 in Part I. of this subject.

Aggregation Studies: MR and MA With Poxvirus

1967 ◽  
Vol 25 ◽  
pp. 90-91
Author(s):  
D. G. Sharp ◽  
Kwang Soo Kim
Keyword(s):  
Cell Interaction ◽  
Actual State ◽  
New Host ◽  
Virus Particles ◽  
Particle Level ◽  
Dilute Suspension ◽  
The Individual ◽  
Quality Factor Q ◽  
Made In ◽  
Number Of Particles

The only instrument that gives direct information about virus-cell interaction at the individual particle level is the electron microscope. The counting of virus particles sedimented from dilute suspension for electron microscopy showed first that rather few of them produce plaques. Soon it was shown that the quality factor (Q=PFU/particles) was not a constant. It changed during the repeated passages required for adaptation of a virus to growth in a new host cell. More recently changes in Q have been observed when changes are made in the state of aggregation of the virus particles. These changes, their measurement and their meaning are the substance of this paper.Virus particles sedimented from dilute suspension fall upon a flat surface producing a pattern that shows coincidence pairs, triplets, etc., produced by chance falling together of separate particles. The number of these is small and it can be calculated. Aggregation in excess of this amount is true aggregation. It is the actual state of the virus particle population that encounters the cells of the monolayer on which plaques appear. From electron micrographs the frequency Ni of groups containing i particles is determined together with the total number of particles.

scholarly journals An account of some experiments made in the West Indies and North America, to determine the relative magnetic forces, in the Years 1831, 32, and 33

1837 ◽  
Vol 3 ◽  
pp. 253-253
Keyword(s):  
North America ◽  
West Indies ◽  
Great Care ◽  
The West ◽  
Magnetic Forces ◽  
The Mean ◽  
Made In

The experiments of which the results are given in this paper were made by Mr. James Napier, late Master of H. M. S. Winchester. The needles were precisely similar to those used in the experiments described by the author in a former paper; and the observations were made with great care, and repeated several times at the same places; by which it appeared that the intensities of the needles continued unchanged during the whole period of the experiments; and the mean of all those made at one place was taken as the result. From these the relative forces at different places were computed, and stated in the form of a table.

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