scholarly journals Ice Nuclei in the Ultramicroscope and the Atmosphere

1949 ◽  
Vol 1 (6) ◽  
pp. 310-314
Author(s):  
E. M. Fournier d’Albe
Keyword(s):  
Present Article ◽  
Ice Crystals ◽  
Small Scale ◽  
Ice Nuclei ◽  
Laboratory Results ◽  
Made In ◽  
Stimulation Of

AbstractVarious attempts have been made in recent years to overcome the difficulties inherent in the study of clouds by reproducing them on a small scale in the laboratory. The present article briefly reviews some of these experiments, particularly those relating to the formation of ice crystals, and discusses the extent to which the laboratory results accord with what is known of natural clouds. Recent experiments on the artificial stimulation of rainfall are also examined for the light they throw on the part played by ice nuclei in the formation of rain.

scholarly journals Ice Nuclei in the Ultramicroscope and the Atmosphere

1949 ◽  
Vol 1 (06) ◽  
pp. 310-314 ◽  
Author(s):  
E. M. Fournier d’Albe
Keyword(s):  
Present Article ◽  
Ice Crystals ◽  
Small Scale ◽  
Ice Nuclei ◽  
Laboratory Results ◽  
Made In ◽  
Stimulation Of

AbstractVarious attempts have been made in recent years to overcome the difficulties inherent in the study of clouds by reproducing them on a small scale in the laboratory. The present article briefly reviews some of these experiments, particularly those relating to the formation of ice crystals, and discusses the extent to which the laboratory results accord with what is known of natural clouds. Recent experiments on the artificial stimulation of rainfall are also examined for the light they throw on the part played by ice nuclei in the formation of rain.

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 Simulating gas-aerosol-cirrus interactions: Process-oriented microphysical model and applications

2003 ◽  
Vol 3 (4) ◽  
pp. 4129-4181
Author(s):  
B. Kärcher
Keyword(s):  
Ice Crystals ◽  
Small Scale ◽  
Particle Interactions ◽  
Ice Nuclei ◽  
Scale Temperature ◽  
Chemical Equations ◽  
Tropopause Region ◽  
Formation And Evolution ◽  
Process Oriented ◽  
Phase Chemistry

Abstract. This work describes a process-oriented, microphysical-chemical model to simulate the formation and evolution of aerosols and ice crystals under the conditions prevailing in the upper troposphere and lower stratosphere. The model can be run as a box model or along atmospheric trajectories, and considers mixing, gas phase chemistry of aerosol precursors, binary homogeneous aerosol nucleation, homogeneous and heterogeneous ice nucleation, coagulation, condensation and dissolution, gas retention during particle freezing, gas trapping in growing ice crystals, and reverse processes. Chemical equations are solved iteratively using a second order implicit integration method. Gas-particle interactions and coagulation are treated over various size structures, with fully mass conserving and non-iterative numerical solution schemes. Particle types include quinternary aqueous solutions composed of H2SO4, HNO3, HCl, and HBr with and without insoluble components, insoluble aerosol particles, and spherical or columnar ice crystals deriving from each aerosol type separately. Three case studies are discussed in detail to demonstrate the potential of the model to simulate real atmospheric processes and to highlight current research topics concerning aerosol and cirrus formation near the tropopause. Emphasis is placed on how the formation of cirrus clouds and the scavenging on nitric acid in cirrus depends on small-scale temperature fluctuations and the presence of efficient ice nuclei in the tropopause region, corroborating and partly extending the findings of previous studies.

scholarly journals Simulating gas-aerosol-cirrus interactions: Process-oriented microphysical model and applications

2003 ◽  
Vol 3 (5) ◽  
pp. 1645-1664 ◽  
Author(s):  
B. Kärcher
Keyword(s):  
Ice Crystals ◽  
Small Scale ◽  
Particle Interactions ◽  
Ice Nuclei ◽  
Scale Temperature ◽  
Chemical Equations ◽  
Tropopause Region ◽  
Formation And Evolution ◽  
Process Oriented ◽  
Phase Chemistry

Abstract. This work describes a process-oriented, microphysical-chemical model to simulate the formation and evolution of aerosols and ice crystals under the conditions prevailing in the upper troposphere and lower stratosphere. The model can be run as a box model or along atmospheric trajectories, and considers mixing, gas phase chemistry of aerosol precursors, binary homogeneous aerosol nucleation, homogeneous and heterogeneous ice nucleation, coagulation, condensation and dissolution, gas retention during particle freezing, gas trapping in growing ice crystals, and reverse processes. Chemical equations are solved iteratively using a second order implicit integration method. Gas-particle interactions and coagulation are treated over various size structures, with fully mass conserving and non-iterative numerical solution schemes. Particle types include quinternary aqueous solutions composed of H2SO4, HNO3, HCl, and HBr with and without insoluble components, insoluble aerosol particles, and spherical or columnar ice crystals deriving from each aerosol type separately. Three case studies are discussed in detail to demonstrate the potential of the model to simulate real atmospheric processes and to highlight current research topics concerning aerosol and cirrus formation near the tropopause. Emphasis is placed on how the formation of cirrus clouds and the scavenging of nitric acid in cirrus depends on small-scale temperature fluctuations and the presence of efficient ice nuclei in the tropopause region, corroborating and partly extending the findings of previous studies.

Small-Scale Cultural Tourism Events: Residents' Perceptions on Their Quality and Impacts

2020 ◽  
Vol 25 (2) ◽  
pp. 283-293
Author(s):  
Maria Doumi ◽  
Anna Kyriakaki ◽  
Theodoros Stavrinoudis
Keyword(s):  
Cluster Analysis ◽  
Present Article ◽  
Natural Environment ◽  
Local Level ◽  
Tourism Development ◽  
Cultural Tourism ◽  
Small Scale ◽  
Primary Research ◽  
Local Society ◽  
Cultural Events

In the present article researchers feature the examination of the opinions and attitudes of the residents of Chios island in Greece. It is based on the investigation of both the characteristics (quality, potential, organization) of the island's main annual cultural events (Rocket War, Agas, and Mostra) and their possible impact on the local society, economy, tourism, and natural environment. Cluster analysis was used to classify the residents under three groups: Embracers, Realists, Neutrals. Each group has particular characteristics and a clearly defined opinion about local cultural tourism events and their impact on a local level. According to the main findings of the primary research some particularly interesting aspects of the effects of local cultural tourism events both on the local level and on the island's tourism development emerge. The conclusions drawn from the elaboration of such findings afford an opportunity to understand better the general impact of cultural events and by the same token to assist government bodies, residents, and other stakeholders in maximizing benefits, whenever possible.

The Mystery of Ice Crystal Multiplication in a Laboratory Experiment

2013 ◽  
Vol 71 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Gianni Santachiara ◽  
Franco Belosi ◽  
Franco Prodi
Keyword(s):  
Laboratory Experiment ◽  
Supercooled Liquid ◽  
Ice Crystals ◽  
Formation Processes ◽  
Ice Crystal ◽  
Droplet Vaporization ◽  
Ice Nuclei ◽  
Cold Room ◽  
The Mean ◽  
Ice Multiplication

Abstract This paper addresses the problem of the large discrepancies between ice crystal concentrations in clouds and the number of ice nuclei in nearby clear air reported in published papers. Such discrepancies cannot always be explained, even by taking into account both primary and secondary ice formation processes. A laboratory experiment was performed in a cylindrical column placed in a cold room at atmospheric pressure and temperature in the −12° to −14°C range. Supercooled droplets were nucleated in the column, in the absence of aerosol ice nuclei, by injecting ice crystals generated outside in a small syringe. A rapid increase in the ice crystal concentration was observed in the absence of any known ice multiplication. The ratio between the mean number of ice crystals in the column, after complete droplet vaporization, and the number of ice crystals introduced in the column was about 10:1. The presence of small ice crystals (introduced at the top of the column) in the unstable system (supercooled droplets) appears to trigger the transformation in the whole supercooled liquid cloud. A possible explanation could be that the rapidly evaporating droplets cool sufficiently to determine a homogeneous nucleation.

Oscillations in Closed Surge Tanks

1943 ◽  
Vol 10 (4) ◽  
pp. A183-A186
Author(s):  
A. M. Binnie
Keyword(s):  
Small Scale ◽  
Maximum Pressure ◽  
Surge Tank ◽  
Compression And Expansion ◽  
Made In

Abstract The existing methods of predicting the oscillations in a closed surge tank are very lengthy unless drastic simplifications are made. In this paper a new and quick procedure is explained for calculating the maximum pressure and expansion of the air, which result from a sudden shutdown of the plant. Friction is taken into account, both in the pipe and also in any arrangement placed between the pipe and the tank to damp the oscillations, but the compression and expansion of the air must be assumed isothermal. Small-scale experiments confirmed the expectation that the observed maximum pressures would be greater than the theoretical. The shutdown of a big plant is, however, not instantaneous, and the theory may be expected to yield results sufficiently accurate for the purpose in view.

scholarly journals Characterization of Arctic mixed-phase cloud properties at small scale and coupling with satellite remote sensing

2017 ◽  
Author(s):  
Guillaume Mioche ◽  
Olivier Jourdan ◽  
Julien Delanoë ◽  
Christophe Gourbeyre ◽  
Guy Febvre ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Crystal Size ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Small Scale ◽  
Vertical Profiles ◽  
Liquid Droplets ◽  
Ice Crystal ◽  
High Concentration ◽  
Ice Crystal Size

Abstract. This study aims to characterize the microphysical and optical properties of ice crystals and supercooled liquid droplets within low-level Arctic mixed-phase clouds (MPC). We compiled and analyzed cloud in situ measurements from 4 airborne campaigns (18 flights, 71 vertical profiles in MPC) over the Greenland Sea and the Svalbard region. Cloud phase discrimination and representative vertical profiles of number, size, mass and shapes of ice crystals and liquid droplets are assessed. The results show that the liquid phase dominates the upper part of the MPC with high concentration of small droplets (120 cm−3, 15&tinsp;μm), and averaged LWC around 0.2 g m−3. The ice phase is found everywhere within the MPC layers, but dominates the properties in the lower part of the cloud and below where ice crystals precipitate down to the surface. The analysis of the ice crystal morphology highlights that irregulars and rimed are the main particle habit followed by stellars and plates. We hypothesize that riming and condensational growth processes (including the Wegener-Bergeron-Findeisein mechanism) are the main growth mechanisms involved in MPC. The differences observed in the vertical profiles of MPC properties from one campaign to another highlight that large values of LWC and high concentration of smaller droplets are possibly linked to polluted situations which lead to very low values of ice crystal size and IWC. On the contrary, clean situations with low temperatures exhibit larger values of ice crystal size and IWC. Several parameterizations relevant for remote sensing or modeling are also determined, such as IWC (and LWC) – extinction relationship, ice and liquid integrated water paths, ice concentration and liquid water fraction according to temperature. Finally, 4 flights collocated with active remote sensing observations from CALIPSO and CloudSat satellites are specifically analyzed to evaluate the cloud detection and cloud thermodynamical phase DARDAR retrievals. This comparison is valuable to assess the sub-pixel variability of the satellite measurements as well as their shortcomings/performance near the ground.

The Ancient Cart-tracks of Malta

Antiquity ◽  
1954 ◽  
Vol 28 (110) ◽  
pp. 91-98 ◽  
Author(s):  
H. S. Gracie
Keyword(s):  
Agricultural Soil ◽  
Field Work ◽  
Present Writer ◽  
Small Scale ◽  
Far North ◽  
South Eastern ◽  
Close Proximity ◽  
Made In

The barren hill-tops of Malta are scored in many places by ancient ruts cut deeply into the rock. They can be seen also on the slopes and on the lower plains, but less frequently because these areas are normally under agricultural soil. They always occur in pairs from 52 to 58 inches apart and were quite clearly used by vehicles. They have been discussed in print for 300 years but no agreement has been reached on how, when or why they were made or what vehicles used them. In fact, there are as many theories as there are authors. Of these writers only Captain E. G. Fenton and Professor Sir T. Zammit appear to have done any serious field work, and none has published a map. The present writer, therefore, decided to attempt the laborious task of plotting them, making such other observations and measurements as he could. Zammit, in the paper cited, reproduced some excellent photographs from both the ground and the air, to which the reader is referred.Time did not permit an examination of the whole island and few observations were made in the low-lying south-eastern part. A fairly intensive survey was made of the high ground as far north as the Baida Ridge, which joins the northern shores of Ghain Tuffieha Bay and St. Paul’s Bay. Two portions of the map are reproduced here. Where there are a number of parallel tracks in close proximity they are shown on the map as one on account of the necessarily small scale used. The gaps in the routes are mainly due to cultivated patches, and no attempt has been made to bridge them by conjecture.

scholarly journals Causes of diagnostic pitfalls upon analysis results of «physicians’ causes»

2003 ◽  
Vol 2 (2) ◽  
pp. 56-61
Author(s):  
A. I. Osipov ◽  
Yu. N. Bunin ◽  
S. Yu. Kladov ◽  
A. S. Sokolov ◽  
A. D. Shnayder
Keyword(s):  
Medical Errors ◽  
Final Diagnosis ◽  
Perforated Ulcer ◽  
Medical Aid ◽  
Methodological Errors ◽  
Laboratory Results ◽  
Tomsk Region ◽  
Civil Cases ◽  
Diagnostic Pitfalls ◽  
Made In

130 criminal and civil cases had been maintained against physicians in Tomsk region within 1996—2002. There were pitfalls in diagnoses and wrong medical aid in 59 (45,4%) cases. Across diagnostic pitfalls, such as incomplete examination of patients, incomplete registration of laboratory results etc., there were methodological errors. It is known that diagnosis process proceeds in hypothesis form at all stages. While obtaining the history a physician is guided by suppositions arising during inquiring a patient. These suppositions are later verified in the process of an objective examination of the patient. Therefore the most frequent reasons of medical errors are the final diagnosis on the basis of the history and physicians’ inability to use the diagnostic suppositions while diagnosing at all stages. The majority of pitfalls has been made in diagnoses of appendicitis, stomach and duodenum perforated ulcer.

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