In hydrodynamics, a plume or a column is a vertical body of one fluid moving through another. Several effects control the motion of the fluid, including momentum (inertia), diffusion and buoyancy. Pure jets and pure plumes define flows that are driven entirely by momentum and buoyancy effects, respectively. Flows between these two limits are usually described as forced plumes or buoyant jets. "Buoyancy is defined as being positive" when, in the absence of other forces or initial motion, the entering fluid would tend to rise. Situations where the density of the plume fluid is greater than its surroundings, but the flow has sufficient initial momentum to carry it some distance vertically, are described as being negatively buoyant.
Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that include algorithms to solve the mathematical equations that govern the pollutant dispersion. The dispersion models are used to estimate the downwind ambient concentration of air pollutants or toxins emitted from sources such as industrial plants, vehicular traffic or accidental chemical releases. They can also be used to predict future concentrations under specific scenarios. Therefore, they are the dominant type of model used in air quality policy making. They are most useful for pollutants that are dispersed over large distances and that may react in the atmosphere. For pollutants that have a very high spatio-temporal variability and for epidemiological studies statistical land-use regression models are also used.
An urban canyon is a place where the street is flanked by buildings on both sides creating a canyon-like environment, evolved etymologically from the Canyon of Heroes in Manhattan. Such human-built canyons are made when streets separate dense blocks of structures, especially skyscrapers. Other examples include the Magnificent Mile in Chicago, Los Angeles' Wilshire Boulevard corridor, Toronto's Financial District, and Hong Kong's Kowloon and Central districts.
Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. Computer models are required to conduct this analysis, because of the complex variables involved, including vehicle emissions, vehicle speed, meteorology, and terrain geometry. Line source dispersion has been studied since at least the 1960s, when the regulatory framework in the United States began requiring quantitative analysis of the air pollution consequences of major roadway and airport projects. By the early 1970s this subset of atmospheric dispersion models was being applied to real-world cases of highway planning, even including some controversial court cases.
The Atmospheric Dispersion Modelling Liaison Committee (ADMLC) is composed of representatives from government departments, agencies and private consultancies. The ADMLC's main aim is to review current understanding of atmospheric dispersion and related phenomena for application primarily in the authorization or licensing of pollutant emissions to the atmosphere from industrial, commercial or institutional sites.
The National Environmental Research Institute of Denmark, abbreviated NERI, was an independent research institute under the Ministry of the Environment. It was created in 1989 by merging the existing laboratories of the Environmental Protection Agency, which covered marine, freshwater and air pollution, soil ecology and analytical chemistry, with the Danish Wildlife Research, under the Ministry of Agriculture. The laboratories were physically located on Risø, in Silkeborg and on Kalø, north of Aarhus. In 1995, Greenland Biological Research laboratory was added.
The ADMS 3 is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously from point, line, volume and area sources, or intermittently from point sources. It was developed by Cambridge Environmental Research Consultants (CERC) of the UK in collaboration with the UK Meteorological Office, National Power plc and the University of Surrey. The first version of ADMS was released in 1993. The version of the ADMS model discussed on this page is version 3 and was released in February 1999. It runs on Microsoft Windows. The current release, ADMS 5 Service Pack 1, was released in April 2013 with a number of additional features.
The AERMOD atmospheric dispersion modeling system is an integrated system that includes three modules:
NAME atmospheric pollution dispersion model was first developed by the UK's Met Office in 1986 after the nuclear accident at Chernobyl, which demonstrated the need for a method that could predict the spread and deposition of radioactive gases or material released into the atmosphere.
A line source, as opposed to a point source, area source, or volume source, is a source of air, noise, water contamination or electromagnetic radiation that emanates from a linear (one-dimensional) geometry. The most prominent linear sources are roadway air pollution, aircraft air emissions, roadway noise, certain types of water pollution sources that emanate over a range of river extent rather than from a discrete point, elongated light tubes, certain dose models in medical physics and electromagnetic antennas. While point sources of pollution were studied since the late nineteenth century, linear sources did not receive much attention from scientists until the late 1960s, when environmental regulations for highways and airports began to emerge. At the same time, computers with the processing power to accommodate the data processing needs of the computer models required to tackle these one-dimensional sources became more available.
DISPERSION21 is a local scale atmospheric pollution dispersion model developed by the air quality research unit at Swedish Meteorological and Hydrological Institute (SMHI), located in Norrköping.
Fundamentals of Stack Gas Dispersion is a book devoted to the fundamentals of air pollution dispersion modeling of continuous, buoyant pollution plumes from stationary point sources. The first edition was published in 1979. The current fourth edition was published in 2005.
The Air Pollution Index is a simple and generalized way to describe the air quality, which is used in Malaysia. It is calculated from several sets of air pollution data and was formerly used in mainland China and Hong Kong. In mainland China the API was replaced by an updated air quality index in early 2012 and on 30 December 2013 Hong Kong moved to a health based index.
The following outline is provided as an overview of and topical guide to air pollution dispersion: In environmental science, air pollution dispersion is the distribution of air pollution into the atmosphere. Air pollution is the introduction of particulates, biological molecules, or other harmful materials into Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, and the natural or built environment. Air pollution may come from anthropogenic or natural sources. Dispersion refers to what happens to the pollution during and after its introduction; understanding this may help in identifying and controlling it.
ISC3 (Industrial Source Complex) model is a popular steady-state Gaussian plume model which can be used to assess pollutant concentrations from a wide variety of sources associated with an industrial complex.
SAFE AIR is an advanced atmospheric pollution dispersion model for calculating concentrations of atmospheric pollutants emitted both continuously or intermittently from point, line, volume and area sources. It adopts an integrated Gaussian puff modeling system. SAFE AIR consists of three main parts: the meteorological pre-processor WINDS to calculate wind fields, the meteorological pre-processor ABLE to calculate atmospheric parameters and a lagrangian multisource model named P6 to calculate pollutant dispersion. SAFE AIR is included in the online Model Documentation System (MDS) of the European Environment Agency (EEA) and of the Italian Agency for the Protection of the Environment (APAT).
Turbulent diffusion is the transport of mass, heat, or momentum within a system due to random and chaotic time dependent motions. It occurs when turbulent fluid systems reach critical conditions in response to shear flow, which results from a combination of steep concentration gradients, density gradients, and high velocities. It occurs much more rapidly than molecular diffusion and is therefore extremely important for problems concerning mixing and transport in systems dealing with combustion, contaminants, dissolved oxygen, and solutions in industry. In these fields, turbulent diffusion acts as an excellent process for quickly reducing the concentrations of a species in a fluid or environment, in cases where this is needed for rapid mixing during processing, or rapid pollutant or contaminant reduction for safety.
The Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT) is a computer model that is used to compute air parcel trajectories to determine how far and in what direction a parcel of air, and subsequently air pollutants, will travel. HYSPLIT is also capable of calculating air pollutant dispersion, chemical transformation, and deposition. The HYSPLIT model was developed by the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory and the Australian Bureau of Meteorology Research Centere in 1998. The model derives its name from the usage of both Lagrangian and Eulerian approaches.
A land use regression model is an algorithm often used for analyzing pollution, particularly in densely populated areas.
