Smoke Cloud Research Articles

Regaining profiles of extinction coefficients of optically dense scattering media in laser location measurements

We suggest a procedure for regaining spectral values of the extinction coefficients e(r) of optically dense scattering media in laser location measurements. Allowance is made for the contribution of multiple scattering to a recorded signal and its correction for the degree of change of the qualitative composition of the scattering medium. The procedure can increase the accuracy of regaining e(r) and eliminate the “edge effect” at the end of the probed path. The latter is achieved by determining a calibration constant from the transparency value of the whole probing range, which is calculated from back-scattered signals corrected based on the constancy of the lidar ratio. We present an algorithm for calculating the correction coefficient. The efficiency of regaining profiles of e(r) is estimated using the atmospheric situation of a pure atmosphere and an extended smoke cloud arising from forest fires as an example.

London Fuel Tank Explosion Recorded by Short-period Seismic Stations at 500-km Distance

Research Article| May 01, 2007 London Fuel Tank Explosion Recorded by Short-period Seismic Stations at 500-km Distance Klaus-G. Hinzen Klaus-G. Hinzen Earthquake Geology Division Cologne University Vinzenz-Pallotti-Str. 26 51429 Bergisch Gladbach, Germany hinzen@uni-koeln.de Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2007) 78 (3): 383–388. https://doi.org/10.1785/gssrl.78.3.383 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Klaus-G. Hinzen; London Fuel Tank Explosion Recorded by Short-period Seismic Stations at 500-km Distance. Seismological Research Letters 2007;; 78 (3): 383–388. doi: https://doi.org/10.1785/gssrl.78.3.383 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search On Sunday, 11 December 2005, at about 6 am UTC, several explosions rocked one of the five largest fuel depots in the United Kingdom, approximately 40 km north of London in Buncefield, Hertfordshire. Some media sources claimed that the resulting fire was the largest in peacetime Europe. A handful of families were temporarily homeless because of the fire, and many more residents within a three-mile radius of the Hemel Hempstead site saw their homes damaged. The blast also destroyed part of the Luton Airport terminal, and the oil fire sent thick clouds of black smoke over London and South England... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Climatic consequences of regional nuclear conflicts

Abstract. We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and long-lasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter" simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes are more long-lasting because the older models did not adequately represent the stratospheric plume rise.

Death in the Haymarket: A Story of Chicago, the First Labor Movement, and the Bombing That Divided Gilded Age America by James Green

Book Reviews 175 Negro Exposition of 1940, a relatively unsuccessful effort to build upon the "celebration of the seventy-fifth anniversary of the end of the Civil War and blacks' official emancipation from slavery" (p. 20). Although it did evoke a growing interest in history, the exposition's shortcomings as a celebration of contemporary culture actually fostered more successful efforts at self-awareness elsewhere. Green then takes readers on a tour of Chicago's hvely music scene, including gospel, blues, and other African American genres. Music becomes a form of expression that emphasizes the common experience and self-image of its hsteners, paralleling the efforts of the printed word. In what are truly outstanding chapters, Green explores the stories of two media innovators. Founded in 1919, Claude Barnett's Associated Negro Press hnked together dozens of newspapers, providing them with features and news stories that made local events national and vice versa. John Johnson's Ebony magazine first hit the newsstands in 1945. The magazine's embrace of celebrities and consumer goods appealed to a more middle-class audience, while its companion publication, Jet, was more edgy. Selling the Race then moves on to the Emmett Till affair, the 1955 murder case in which an African American youth from Chicago was lynched in Mississippi after he allegedly whistled at a white woman, and the 1955 riots that accompanied the effort to integrate pubhc housing. These stories are linked by a running commentary that delineates the difficulties involved in creating a national black culture within the historic constraints of "clientage," an accommodation based on peacefully institutionahzed subservience. The writing is crisp, the topics were chosen with great thought, the research is thorough, and the arguments are logical. This is amarvelous book, amust-read for everyone interested in the history of Chicago, aswell asmid-century African American history. Perry R. Duis, Professor of History University of Illinois at Chicago James Green. Death in theHaymarket: A Story of Chicago, theFirst Labor Movement, and the Bombing that Divided Gilded Age America. New York: Pantheon Books, 2006. Pp. 383. Bibliography. Illustrations. Index. Notes. Cloth, $26.95. On the evening of May 4, 1886, a bomb exploded at a workers' rally in Chicago's Haymarket Square. Dozens of pohce officers were injured and seven died of their wounds. Rally participants also suffered 176 Michigan Historical Review casualties. Among the victims was the labor movement itself. The bombing triggered cries for revenge, as the pohce unleashed a witch hunt against labor organizers and immigrant workers. Convicted by the press and pubhc opinion before their trial began, four anarchist workers went to the gallows. The events in Chicago?the labor conflict known as the "Great Upheaval" in the spring of 1886, the Haymarket bombing, and the ensuing red scare, trial, and hangings? mark one of the most dramatic episodes in America's emergence as a modern industrial society. As the title suggests, James Green's book is first about the city of Chicago, whose enormous industries produced vast wealth and promise, along with dark clouds of gaseous smoke and bitter class divisions. The first half of the book explores the world of the ethnically diverse working class, with its Bohemian militias, German meeting halls, and complex mix of radical and labor organizations. The account of the Great Upheaval, where the pohce met workers' strikes for the eight-hour day with truncheons and revolvers, helps explain why all parties in the contest tended to interpret events in terms of cataclysmic violence. The terror struck on May 4, and Green does a masterful job of capturing the human drama, from the bomb that arched over Haymarket to the trap doors of the gallows that fell beneath the convicted labor leaders. The events at Haymarket had a powerful impact on the national labor movement. It would take more than a generation for the trade union movement in Detroit and other midwestern cities to recover from this tragedy. Haymarket's history also poses large questions about immigrant rights, freedom of speech, and legal protections in a time of terror and mass hysteria. Other sources that discuss these events include: The Haymarket Tragedy by Paul Avrich, which provides an in-depth analysis of...

Patience is a Virtue

Laura Morgan, MD Winter 2007 - Volume 11 Number 1 Patience is a virtue we struggle to express, A gift we give ourselves and others in times of distress, A cleansing breath of oxygen through rushing clouds of smoke, A window on the Absol

Inventing pollution: coal, smoke, and culture in Britain since 1800

Britain's supremacy in the nineteenth century depended in large part on its vast deposits of coal. This coal not only powered steam engines in factories, ships, and railway locomotives but also warmed homes and cooked food. As coal consumption skyrocketed, the air in Britain's cities and towns became filled with ever-greater and denser clouds of smoke. In this far-reaching study, Peter Thorsheim explains that, for much of the nineteenth century, few people in Britain even considered coal smoke to be pollution. To them, pollution meant miasma: invisible gases generated by decomposing plant and animal matter. Far from viewing coal smoke as pollution, most people considered smoke to be a valuable disinfectant, for its carbon and sulfur were thought capable of rendering miasma harmless. Inventing Pollution examines the radically new understanding of pollution that emerged in the late nineteenth century, one that centered not on organic decay but on coal combustion. This change, as Peter Thorsheim argues, gave birth to the smoke-abatement movement and to new ways of thinking about the relationships among humanity, technology, and the environment.

Measurement of the dimensionless extinction coefficient of soot within laminar diffusion flames

The dimensionless extinction coefficient ( K e) of soot must be known to quantify laser extinction measurements of soot concentration and to predict optical attenuation through smoke clouds. Previous investigations have measured K e for post-flame soot emitted from laminar and turbulent diffusion flames and smoking laminar premixed flames. This paper presents the first measurements of soot K e from within laminar diffusion flames, using a small extractive probe to withdraw the soot from the flame. To measure K e, two laser sources (635 nm and 1310 nm) were coupled to a transmission cell, followed by gravimetric sampling. Coannular diffusion flames of methane, ethylene and nitrogen-diluted kerosene burning in air were studied, together with slot flames of methane and ethylene. K e was measured at the radial location of maximum soot volume fraction at several heights for each flame. Results for K e at both 635 nm and 1310 nm for ethylene and kerosene coannular flames were in the range of 9–10, consistent with the results from previous studies of post-flame soot. The ethylene slot flame and the methane flames have lower K e values, in some cases as low as 2.0. These lower values of K e are found to result from the contributions of (a) the condensation of PAH species during the sampling of soot, (b) the wavelength-dependent absorptivity of soot precursor particles, and, in the case of methane, (c) the negligible contribution of soot scattering to the extinction coefficient. RDG calculations of soot scattering, in combination with the measured K e values, imply that the soot refractive index is in the vicinity of 1.75–1.03 i at 635 nm.

Optical properties of humic-like substances (HULIS) in biomass-burning aerosols

Abstract. We present here the optical properties of humic-like substances (HULIS) isolated from the fine fraction of biomass-burning aerosol collected in the Amazon basin during the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia – SMOke aerosols, Clouds, rainfall and Climate) experiment in September 2002. From the isolated HULIS, aerosol particles were generated and their scattering and absorption coefficients measured. The size distribution and mass of the particles were also recorded. The value of the index of refraction was derived from "closure" calculations based on particle size, scattering and absorption measurements. On average, the complex index of refraction at 532 nm of HULIS collected during day and nighttime was 1.65–0.0019i and 1.69–0.0016i, respectively. In addition, the imaginary part of the complex index of refraction was calculated using the measured absorption coefficient of the bulk HULIS. The mass absorption coefficient of the HULIS at 532 nm was found to be quite low (0.031 and 0.029 m2 g−1 for the day and night samples, respectively). However, due to the high absorption Ångström exponent (6–7) of HULIS, the specific absorption increases substantially towards shorter wavelengths (~2–3 m2 g−1 at 300 nm), causing a relatively high (up to 50%) contribution to the light absorption of our Amazonian aerosol at 300 nm. For the relative contribution of HULIS to light absorption in the entire solar spectrum, lower values (6.4–8.6%) are obtained, but those are still not negligible.

Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin. I: Comparison and field calibration of absorption measurement techniques

Abstract. Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on a filter substrate before measurement. Recently, a 7-wavelength (λ) Aethalometer became commercially available, which covers the visible (VIS) to near-infrared (NIR) spectral range (λ=450–950 nm), and laboratory calibration studies improved the degree of confidence in these measurement techniques. However, the applicability of the laboratory calibration factors to ambient conditions has not been investigated thoroughly yet. As part of the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia – SMOke aerosols, Clouds, rainfall and Climate) campaign from September to November 2002 in the Amazon basin we performed an extensive field calibration of a 1-λ PSAP and a 7-λ Aethalometer utilizing a photoacoustic spectrometer (PAS, 532 nm) as reference device. Especially during the dry period of the campaign, the aerosol population was dominated by pyrogenic emissions. The most pronounced artifact of integrating-plate type attenuation techniques (e.g. Aethalometer, PSAP) is due to multiple scattering effects within the filter matrix. For the PSAP, we essentially confirmed the laboratory calibration factor by Bond et al. (1999). On the other hand, for the Aethalometer we found a multiple scattering enhancement of 5.23 (or 4.55, if corrected for aerosol scattering), which is significantly larger than the factors previously reported (~2) for laboratory calibrations. While the exact reason for this discrepancy is unknown, the available data from the present and previous studies suggest aerosol mixing (internal versus external) as a likely cause. For Amazonian aerosol, we found no absorption enhancement due to hygroscopic particle growth in the relative humidity (RH) range between 40% and 80%. However, a substantial bias in PSAP sensitivity that correlated with both RH and temperature (T) was observed for 20%<RH<30% and 24°C<T<26°C, respectively. In addition, both PSAP and Aethalometer demonstrated no sensitivity to gaseous adsorption. Although very similar in measurement principle, the PSAP and Aethalometer require markedly different correction factors, which is probably due to the different filter media used. Although on-site calibration of the PSAP and Aethalometer is advisable for best data quality, we recommend a set of "best practice" correction factors for ambient sampling based on the data from the present and previous studies. For this study, the estimated accuracies of the absorption coefficients determined by the PAS, PSAP and Aethalometer were 10, 15 and 20% (95% confidence level), respectively.

Size distribution and hygroscopic properties of aerosol particles from dry-season biomass burning in Amazonia

Abstract. Aerosol particle number size distributions and hygroscopic properties were measured at a pasture site in the southwestern Amazon region (Rondonia). The measurements were performed 11 September-14 November 2002 as part of LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia - SMOke aerosols, Clouds, rainfall and Climate), and cover the later part of the dry season (with heavy biomass burning), a transition period, and the onset of the wet period. Particle number size distributions were measured with a DMPS (Differential Mobility Particle Sizer, 3-850nm) and an APS (Aerodynamic Particle Sizer), extending the distributions up to 3.3 µm in diameter. An H-TDMA (Hygroscopic Tandem Differential Mobility Analyzer) measured the hygroscopic diameter growth factors (Gf) at 90% relative humidity (RH), for particles with dry diameters (dp) between 20-440 nm, and at several occasions RH scans (30-90% RH) were performed for 165nm particles. These data provide the most extensive characterization of Amazonian biomass burning aerosol, with respect to particle number size distributions and hygroscopic properties, presented until now. The evolution of the convective boundary layer over the course of the day causes a distinct diel variation in the aerosol physical properties, which was used to get information about the properties of the aerosol at higher altitudes. The number size distributions averaged over the three defined time periods showed three modes; a nucleation mode with geometrical median diameters (GMD) of ~12 nm, an Aitken mode (GMD=61-92 nm) and an accumulation mode (GMD=128-190 nm). The two larger modes were shifted towards larger GMD with increasing influence from biomass burning. The hygroscopic growth at 90% RH revealed a somewhat external mixture with two groups of particles; here denoted nearly hydrophobic (Gf~1.09 for 100 nm particles) and moderately hygroscopic (Gf~1.26). While the hygroscopic growth factors were surprisingly similar over the periods, the number fraction of particles belonging to each hygroscopic group varied more, with the dry period aerosol being more dominated by nearly hydrophobic particles. As a result the total particle water uptake rose going into the cleaner period. The fraction of moderately hygroscopic particles was consistently larger for particles in the accumulation mode compared to the Aitken mode for all periods. Scanning the H-TDMA over RH (30-90% RH) showed no deliquescence behavior. A parameterization of both Gf(RH) and Gf(dp), is given.

An Analysis of Effects of San Diego Wildfire on Ambient Air Quality

The impact of major gaseous and particulate pollutants emitted by the wildfire of October 2003 on ambient air quality and health of San Diego residents before, during, and after the fire are analyzed using data available from the San Diego County Air Pollution Control District and California Air Resources Board. It was found that fine particulate matter (PM) levels exceeded the federal daily 24-hr average standard during the fire. There was a slight increase in some of the gaseous pollutants, such as carbon monoxide, which exceeded federal standards. Ozone (O3) precursors, such as total hydrocarbons and methane gases, experienced elevated concentration during the fire. Fortunately, the absence of sunlight because of the cloud of thick smoke that covered most of the county during the fire appears to have prevented the photochemical conversion of the precursor gases to harmful concentrations of O3. Statistical analysis of the compiled medical surveillance data has been used to establish correlations between pollutant levels in the region and the resultant health problems experienced by the county citizens. The study shows that the increased PM concentration above the federal standard resulted in a significant increase in hospital emergency room visits for asthma, respiratory problems, eye irritation, and smoke inhalation. On the basis of the findings, it is recommended that hospitals and emergency medical facilities engage in pre–event planning that would ensure a rapid response to an impact on the healthcare system as a result of a large wildfire and appropriate agencies engage in the use of all available meteorological forecasting resources, including real–time satellite imaging assets, to accurately forecast air quality and assist firefighting efforts.

Welding and Parkinson disease

The cause of Parkinson disease (PD) remains unknown. Progress has been made on the genetic front with the identification of specific gene mutations (e.g., α-synuclein) associated with familial Parkinson syndromes. Because of their clinical heterogeneity there remains debate as to whether these genetic syndromes are representative of what has been considered classical PD. The identification of mutations in the parkin and LRRK2 genes in both familial and sporadic PD1,2 suggest that genetic mutations may be more common than previously estimated. Despite these advances, at least 80% of PD cases do not have a clear genetic or familial basis. The knowledge that different genetic mutations can produce the PD phenotype suggests that perhaps there is no single clinical entity PD, but rather that PD is an amalgamation of many different conditions that simply have a greater or lesser degree of phenotypic overlap. However, most clinicians and scientists still endorse the classical concept of idiopathic PD. See also pages 2021 and 2033 For the condition generally referred to as idiopathic PD and characterized by asymmetric onset of rest tremor, bradykinesia and rigidity, responsiveness to dopaminergic treatment, and the classic pathology of nigral degeneration with Lewy bodies, the cause remains unknown. Because genetic causes appear identifiable in only a minority of cases, there has been an extensive search for potential environmental causes. This search has been fueled by the identification of individuals who developed parkinsonism following exposure to MPTP through injection drug use and epidemiologic links between PD and environmental exposure to agricultural chemicals. Another environmental topic of recent interest has been the potential relationship between occupational welding fume exposure and PD. Welding fume is the cloud of smoke that is produced when welding metals. This fume, like cigarette smoke, is a combination of many different chemicals in a complex interaction. The …

What matters

Within academic as well as political circles, summoning the events of September 11 has emerged as a common rhetorical device for signaling some deep-seated shift in direction or purpose. In a moment I will myself succumb to the temptation to allegorize the attack. However, my experience of the calamity in New York began in a more prosaic manner. From the proximate yet soft haven of a hotel room in midtown en route from somewhere else to elsewhere, I witnessed the sublime collapse of the twin towers, as did most others, on television. The days to follow offered autumnal weather of such splendor that Central Park at its finest could scarce occupy my consciousness at the same time as did the sickening cloud of smoke to the south and the scream of F-16s incessantly circling Manhattan. At first the event felt like local news: buildings attacked in this town, tunnels and bridges closed to this island, subways and restaurants closed here. It took me a good while — really until I regained distance from New York days later, taking an improvised flight to Chicago from which the view of the Sears Tower suddenly took on the frightening prospect of catastrophic possibility — that I began to sense the national scope of the tragedy and its emerging role as a political and moral watershed.

Smoke distributions from fire plumes in uniform downdraft from a ceiling

This paper describes a reduced-scale study of the contamination field (“smoke”) arising from a fire source in a space where air normally flows vertically at uniform velocity in a near-laminar state from ceiling to floor, as in many industrial clean rooms. While the flames of the fire source were not visually affected by the downdraft of air, the distribution of combustion products (“smoke”), as assessed from the penetration of fire-generated carbon dioxide into the fire space, was strongly affected. The combustion products distributed into umbrella-shaped smoke clouds around the fire source, outside of which the air was not contaminated. The boundaries have been plotted in scaled coordinates, applicable to arbitrary ceiling height and, in one version, also a range of downdraft velocities.

Large-Eddy Simulation: How Large is Large Enough?

The length scale evolution of various quantities in a clear convective boundary layer (CBL), a stratocumulus-topped boundary layer, and three radiatively cooled (“smoke cloud”) convective boundary layers are studied by means of large-eddy simulations on a large horizontal domain (25.6 × 25.6 km2). In the CBL the virtual potential temperature and the vertical velocity fields are dominated by horizontal scales on the order of the boundary layer depth. In contrast, the potential temperature and the specific humidity fields become gradually dominated by mesoscale fluctuations. However, at the mesoscales their effects on the virtual potential temperature fluctuations nearly compensate. It is found that mesoscale fluctuations are negligibly small only for conserved variables that have an entrainment to surface flux ratio close to −0.25, which is about the flux ratio for the buoyancy. In the CBL the moisture and potential temperature flux ratios can have values that significantly deviate from this number. The geometry of the buoyancy flux was manipulated by cooling the clear convective boundary layer from the top, in addition to a positive buoyancy flux at the surface. For these radiatively cooled cases it is found that both the vertical velocity as well as the virtual potential temperature spectra tend to broaden. The role of the buoyancy flux in their respective prognostic variance equations is discussed. It is argued that in the upper part of the clear CBL, where the mean vertical stratification is stable, vertical velocity variance and virtual potential temperature variance cannot be produced simultaneously. For the stratocumulus case, in which latent heat release effects in the cloud layer play an important role in its dynamics, the field of any quantity, except for the vertical velocity, becomes dominated by mesoscale fluctuations. In general, the location of the spectral peak of any quantity becoming constrained by the domain size should be avoided. The answer to the question of how large the LES horizontal domain size should be in order to include mesoscale fluctuations will, on the one hand, depend on the type of convection to be simulated and the kind of physical question one aims to address, and, on the other hand, the time duration of the simulation. Only if one aims to study the dynamics of a dry CBL that excludes moisture, a rather small domain size suffices. In case one aims to examine either the spatial evolution of the fields of any arbitrary conserved scalar in the CBL, or any quantity in stratocumulus clouds except for the vertical velocity, a larger domain size that allows the development of mesoscale fluctuations will be necessary.

Possibility of Fire Accident Analysis in Road Tunnel

Fire modeling in enclosed areas, including railway and road tunnels, is a complex research area with immediate practical benefits of increasing safety of people. This article describes a fire model that characterizes the behavior of smoke and fire in a road tunnel. The model focuses on the effect of air supply and the exhaust system on smoke movement. The model uses the Fire Dynamics Simulator (FDS), a computational fluid dynamics code, to depict a 200 meters long road tunnel. FDS is used to simulate fire dynamics behavior in three different scenarios: natural ventilation, forced ventilation with axial ventilators, and vertical smoke extraction. The simulation has shown that the smoke extraction was high enough to limit the smoke extension in the area between extraction openings. However, the velocity of smoke cloud movement is reduced because of extraction. The main problem found is the slumping effect that keeps the smoke cloud at lower levels inside the tunnel.

The performance of an E?l scheme for the atmospheric boundary layer in a mesoscale model with grid spacing as small as 1?km

¶A new E−l boundary layer scheme is tested within the U.S. Navy’s COAMPS model. The goal is to give COAMPS the capability to simulate mesoscale cellular convection. The new scheme is aimed to be consistent with both classic results for clear entrainment and recent calibrations, derived from large-eddy simulations, for entrainment into smoke clouds and water clouds. A parameter is included in the scheme that allows sub-grid transport to be reduced so that, when the model has 2 km grid spacing or less, more of the transport is forced to occur in resolved convection. At 2 km grid spacing, the scheme allows COAMPS to simulate the break up of a stratocumulus cloud deck into mesoscale cellular convection.

CHEMICAL CHARACTERIZATION OF THE INHALABLE PARTICULATE MATTER IN CITY OF CHILLAN, CHILE

Inhalable particulate matter (PM10) measurements were performed in six different sites in the city of Chillan, Chile, during September 2001 to September 2002. Chemical composition of PM10 was performed to samples of 47 mm diameter Teflon membranes within the city of Chillan. The spatial and temporal variability of the chemical composition of PM10 was evaluated taking into account additional data from meteorology and further air pollutants. The chemical analyses of PM10 showed that carbonaceous substances and crustal material were the most abundant components of PM10 during the winter and summer, respectively. The concentrations of PM10 were higher during the cold season than during the warm season. This was explained mainly due to the massive use of wood as fuel for residential heating within the city of Chillan, producing a dense smoke cloud in those days of atmospheric stability. The PM10 concentrations were higher in the downtown area of the city of Chillan, where also the chemical composition was more variable due to urban traffic and other anthropogenic sources

Transport of forest fire smoke above the tropopause by supercell convection

A recent letter [Fromm et al., 2000] postulated a link between boreal forest fire smoke and observed stratospheric aerosol enhancements in 1998. Therein a case was made that severe convection played a role in the cross‐tropopause transport. A similar occurrence of stratospheric aerosol enhancements in the boreal summer of 2001 was the stimulus to investigate the causal mechanism more deeply. Herein, we show a detailed case illustrating the unambiguous creation of a widespread, dense smoke cloud in the upper troposphere and lower stratosphere (UT/LS) by a Canadian forest fire and explosive convection in May 2001. This event is the apparent common point for several downstream stratospheric mystery cloud observations. Implications of this finding and those pertaining to the boreal summer of 1998 are that convection and boreal biomass burning have an under‐resolved and under‐appreciated impact on the upper troposphere, lower stratosphere, radiative transfer, and atmospheric chemistry.

Calculation and Optimization of the Effective Extinction Cross Section of the Spherical Cold Obscuring Smoke

The smoke is often generated in the battlefield by the smoke ammunition to protect the personnel and equipment against the enemy's optoelectronic systems. The effective extinction cross section is an important parameter of the infrared smoke ammunition. In this paper, the relationships between the effective extinction cross section of a cloud of spherical smoke and the mass of the smoke agent, the radius of the screening smoke and the mass extinction coefficient are discussed. The expressions of the maximal effective extinction cross section is derived. This research will help us to achieve optimal design of the smoke ammunition and to appropriately evaluate the effectiveness of the smoke. Examples are given for two kinds of obscurants.