Showing papers in "Atmospheric Environment in 1973"

TL;DR: In this article, the authors demonstrate the relationship existing between the size of a village, town or city and the magnitude of the urban heat island it produces by analyzing data gathered by automobile traverses in 10 settlements on the St. Lawrence Lowland, whose populations range from 1000 to 2 million inhabitants.

TL;DR: In this article, a practical, multipurpose urban diffusion model (APRAC-1A) was developed and evaluated for predicting concentrations of inert, vehicle-generated pollutants.

TL;DR: In this paper, the adiabatic boundary layer appropriate to flow over an idealised urban terrain has been simulated using a modified version of the system previously used to produce a rural boundary layer simulation.

TL;DR: In this paper, five pressure drop theories and four efficiency theories are evaluated against experimental data taken from the literature and one pressure drop and one efficiency theory are judged "best" and used with an optimization procedure to develop a cyclone design method, which gives a means of calculating the dimensions of a theoretically optimum cyclone for any set of design criteria.

TL;DR: In this article, a simple area source formula X = c Q/u where X is air pollution concentration, Q is source strength per unit area, and u is average wind speed, is studied.

TL;DR: Twenty-nine trace elements in air over the San Francisco Bay Area have been classified into a soil-derived aerosol group, a marine aerosol groups, and a third group of elements whose relative concentrations may be significantly altered by anthropogenic pollution sources.

TL;DR: The authors found that during periods of low precipitation, most Great Plains locations have a significant number of hours with dust, and the median annual hours of dust was 45, but more than 150 dusty hours were recorded in 20 per cent of the reports.

TL;DR: In this article, a method of simulating the urban adiabatic boundary layer is described which meets the conflicting requirements of model scale and wind tunnel size by representing only the lower third of the atmospheric boundary layer.

TL;DR: In this paper, a method was developed for sampling atmospheric oxides and for processing the samples for the determination of stable sulfur isotope ratios, and the effect of concentration, temperature and humidity upon sampling efficiency was described.

TL;DR: Particle resuspension caused by moving-vehicular-generated surface stresses was determined by using solid ZnS tracer particles placed on a road as mentioned in this paper, and the fraction of particles resuspended from the road by the surface stresses were determined using a tracer mass balance.

TL;DR: In this article, the authors applied the nucleation theory to a binary mixture of H 2 O-H 2 SO 4 and H 2O-HNO 3 respectively in air and calculated the formation of critical sized clusters.

TL;DR: In this paper, the concentrations of 18 trace elements in atmospheric aerosol are measured by neutron activation and γ-ray spectrometry using Ge(Li)-detectors, and the trace element concentrations measured in Heidelberg are reported for the measuring period (April-June, 1971) and the average values compared to values given in the literature for Paris.

TL;DR: In this paper, the influence of acidity on solubility was examined by adding HCl to the water solutions, thereby modifying pH over the range between approximately 3 and 7.

TL;DR: In this article, a two-dimensional atmospheric diffusion model for computation of the ambient air concentration of pollutants emitted from an area source is described, where the geostrophic wind, the net heat flux, the surface roughness, the mixing height of the atmosphere and the emission rate of the source are specified.

TL;DR: The results, including approximately 50 per cent mass concentration on the afterfilter, nearly constant Br/Pb ratio at all stations, and the good correlation with CO levels, are consistent with the properties of a condensation aerosol from automobiles.

TL;DR: Experiments with radioactive mercury-tagged fly ash showed that mosses take up and retain mercury to a greater extent than grasses do.

TL;DR: In this article, 11 plant species were exposed to ozone and/or sulfur dioxide to determine if a mixture of the two gases enhanced foliar injury, including tobacco, radish, and alfalfa.

TL;DR: In this article, the use of cellulose filters in high-volume air sampling requires a more powerful cooling system for the vacuum pump than does conventional glass fiber filters, and a complete sampling system is described, including pump, shelter, filter holder and accessories.

TL;DR: The size spectrum of the Pasadena aerosol has been calculated using data from the literature for the size spectra of automobile emissions, soil dust and the marine aerosol and secondary formation processes for paniculate matter significantly modify the primary source spectrum.

TL;DR: In this paper, the authors present a quantitative assessment of the possible importance of these reactions to the overall pollution problem, and the appropriate conditions under which heterogeneous reactions can compete with homogeneous gas-phase reactions in the generation (or removal) of gaseous air pollutants are determined by using a simplified kinetic model together with transition state theory and experimental activation energies to estimate absorption, desorption and reaction rates.

TL;DR: The highest concentrations of mercury were found close to the plants and a rapid decrease was recorded with increased distance from the plants, which probably contributes to the “background” levels in the region and/or to the global circulation.

TL;DR: In this article, the authors investigated the influence of the obliquity of the wind on highway air pollution concentration, and showed that over a wide range of wind directions the concentration distribution can be calculated by a simple approximate formula.

TL;DR: In this paper, a simple extension of Prandtl's mixing length theory is developed and used to derive a set of sufficient conditions for the validity of the diffusion equation which is commonly used to model chemically reactive pollutants in urban atmospheres.

TL;DR: In this article, the original droplets emerging from the nebulizer dry up and form spherical particles of uniform density within a very short time after mixing with clean air of low humidity.

TL;DR: A survey of the available literature on emissions of oxides of nitrogen from moving and stationary sources can be found in this article, where estimates of emissions in the U.K. are given so that the contribution of each source can be evaluated.

TL;DR: In this paper, the theory for measurements with integrating nephelometers is presented in a form which is independent of the characteristics of individual instruments, and its application to two special instruments (Ruppersberg-Nephelometer and Charlson-Nebhelometer) is considered with respect to the problem of calibration with scattering media of known scattering properties.

TL;DR: None of the evidence examined lends much support for the claims made for the success of the Clean Air Act.

TL;DR: In this article, the impact of large aerosol particles on the walls changes the scattering properties of the turbid air under investigation, and the quantitative relationship between the upper boundary radius of the particles and the scattering coefficients or visibilities measured by the nephelometer is given for power law size distributions of the aerosol particle.

TL;DR: In this article, the spectral distribution of visible radiation (270-710 nm) in the direct solar beam was made for three aerosol size distributions at thin and dense concentrations and for solar zenith angles of 30 and 60°.