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Encyclopedia > Atmospheric chemistry
Atmospheric sciences
Meteorology
Climatology
Atmospheric physics
Atmospheric chemistry

Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earth's atmosphere and that of other planets is studied. It is a multidisciplinary field of research and draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and volcanology and other disciplines. Research is increasingly connected with other areas of study such as climatology. Atmospheric sciences is an umbrella term for the study of the atmosphere, its processes, the effects other systems have on the atmosphere, and the effects of the atmosphere on these other systems. ... Satellite image of Hurricane Hugo with a polar low visible at the top of the image. ... Climatology is the study of climate, and is a branch of the atmospheric sciences. ... Atmospheric physics is the application of physics to the study of the atmosphere. ... Meteorology is the scientific study of the atmosphere that focuses on weather processes and forecasting. ... Chemistry (derived from the Arabic word kimia, alchemy, where al is Arabic for the) is the science that deals with the properties of organic and inorganic substances and their interactions with other organic and inorganic substances. ... Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... Interdisciplinary work is that which integrates concepts across different disciplines. ... Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. ... A black hole concept drawing by NASA. Physics (from the Greek, φυσικός (physikos), natural, and φύσις (physis), nature) is the science of the natural world dealing with the fundamental constituents of the universe, the forces they exert on one another, and the results produced by these forces. ... Satellite image of Hurricane Hugo with a polar low visible at the top of the image. ... A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ... To meet Wikipedias quality standards and appeal to a wider international audience, this article may require cleanup. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history and the processes that shape it. ... Volcanology (also spelled vulcanology) is the study of volcanos, lava, magma and related geological phenomena. ... Climatology is the study of climate, and is a branch of the atmospheric sciences. ...


The composition and chemistry of the atmosphere is of importance for several reasons, but primarily because of the interactions between the atmosphere and living organisms. The composition of the Earth's atmosphere has been changed by human activity and some of these changes are harmful to human health, crops and ecosystems. Examples of problems which have been addressed by atmospheric chemistry include acid rain, photochemical smog and global warming. Atmospheric chemistry seeks to understand the causes of these problems, and by obtaining a theoretical understanding of them, allow possible solutions to be tested and the effects of changes in government policy evaluated. Acid rain is defined as any type of precipitation with a pH that is below 5. ... Photochemical smog is the term to represent a multitude of chemical agents which are considered to be detrimental to the environment and health. ... Global mean surface temperatures 1856 to 2005 Mean temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980 Global warming is an increase in the average temperature of the Earths atmosphere and oceans. ...

Schematic of chemical and transport processes related to atmospheric composition.
Schematic of chemical and transport processes related to atmospheric composition.

Contents

Download high resolution version (800x715, 100 KB)Schematic of chemical and transport processes related to atmospheric composition. ... Download high resolution version (800x715, 100 KB)Schematic of chemical and transport processes related to atmospheric composition. ...


Atmospheric composition

Average composition of dry atmosphere, by volume
Gas per NASA
Nitrogen 78.084%
Oxygen 20.946%
Argon 0.934%
Water vapor Highly variable;
typically makes up about 1%
Minor constituents in ppmv.
Carbon Dioxide 350
Neon 18.18
Helium 5.24
Methane 1.7
Krypton 1.14
Hydrogen 0.55

Notes: the concentration of CO2 and CH4 vary by season and location. ppmv represents parts per million by volume.
The mean molecular mass of air is 28.97 g/mol. General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... Water vapor or water vapour, also aqueous vapour, is the gas phase of water. ... Parts per million (ppm) is a measure of concentration that is used where low levels of concentration are significant. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... General Name, Symbol, Number neon, Ne, 10 Chemical series noble gases Group, Period, Block 18, 2, p Appearance colorless Atomic mass 20. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... R-phrases S-phrases , , , Flash point −188 °C Autoignition temperature 537 °C Explosive limits 5–15% Supplementary data page Structure and properties Thermodynamic data Spectral data UV, IR, NMR, MS Related compounds Related alkanes Ethane Propane Related compounds Methanol Chloromethane Except where noted otherwise, data are given for materials in... General Name, Symbol, Number krypton, Kr, 36 Chemical series noble gases Group, Period, Block 18, 4, p Appearance colorless Atomic mass 83. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. ...


History

The ancient Greeks regarded air as one of the four elements, but the first scientific studies of atmospheric composition began in the 18th century. Chemists such as Joseph Priestley, Antoine Lavoisier and Henry Cavendish made the first measurements of the composition of the atmosphere. Joseph Priestley is often credited for the discovery of oxygen. ... Antoine-Laurent de Lavoisier (August 26, 1743 – May 8, 1794) was a French nobleman prominent in the histories of chemistry, finance, biology, and economics. ... Henry Cavendish (October 10, 1731 - February 24, 1810) was a British scientist. ...


In the late 19th and early 20th centuries interest shifted towards trace constituents with very small concentrations. One particularly important discovery for atmospheric chemistry was the discovery of ozone by Christian Friedrich Schoenbein in 1840. For the Moldavian pop group see O-Zone Ozone (O3) is an allotrope of oxygen, the molecule consisting of three oxygen atoms instead of the more stable diatomic O2. ...


In the 20th century atmospheric science moved on from studying the composition of air to a consideration of how the concentrations of trace gases in the atmosphere have changed over time and the chemical processes which create and destroy compounds in the air. Two particularly important examples of this were the explanation of how the ozone layer is created and maintained by Sydney Chapman and Gordon Dobson, and the explanation of Photochemical smog by Haagen-Schmidt. The ozone layer, or ozonosphere, is that part of the Earths stratosphere which contains relatively high concentrations of ozone (O3). ... Sydney Chapman (January 29, 1888 – June 16, 1970) was a British astronomer and geophysicist. ... Photochemical smog is the term to represent a multitude of chemical agents which are considered to be detrimental to the environment and health. ...


In the 21st century the focus is now shifting again. Atmospheric Chemistry is increasingly studied as one part of the Earth System. Instead of concentrating on atmospheric chemistry in isolation the focus is now on seeing it as one part of a single system with the rest of the atmosphere, biosphere and geosphere. An especially important driver for this is the links between chemistry and climate such as the effects of changing climate on the recovery of the ozone hole and vice versa but also interaction of the composition of the atmosphere with the oceans and terrestrial ecosystems. Layers of Atmosphere (NOAA) Earths atmosphere is a layer of gases surrounding the planet Earth and retained by the Earths gravity. ... The biosphere is that part of a planets outer shell—including air, land, surface rocks and water—within which life occurs, and which biotic processes in turn alter or transform. ... Geosphere is another term for the lithosphere of the Earth. ... In ecology, an ecosystem is a community of organisms (plant, animal and other living organisms - also referred as biocenose) together with their environment (or biotope), functioning as a unit. ...


Methodology

Observations, lab measurements and modelling are the three central elements in atmospheric chemistry. Progress in atmospheric chemistry is often driven by the interactions between these components and they form an integrated whole. For example observations may tell us that more of a chemical compound exists than previously thought possible. This will stimulate new modelling and laboratory studies which will increase our scientific understanding to a point where the observations can be explained.


Observation

Observations of atmospheric chemistry are essential to our understanding. Routine observations of chemical composition tell us about changes in atmospheric composition over time. One important example of this is the Keeling Curve - a series of measurements from 1958 to today which show a steady rise in of the concentration of Carbon Dioxide. Observations of atmospheric chemistry are made in observatories such as that on Mauna Loa and on mobile platforms such as aircraft (e.g. the UK's Facility for Airborne Atmospheric Measurements), ships and balloons. Observations of atmospheric composition are increasing made by satellites with important instruments such as GOME and MOPITT giving a global picture of air pollution and chemistry. Surface observations have the advantage that they provide long term records at high time resolution but are limited in the vertical and horizontal space they provide observations from. Some surface based instruments e.g. LIDAR can provide concentration profiles of chemical compounds and aerosol but are still restricted in the horizontal region they can cover. The Keeling Curve is a graph measuring the increase in the levels of carbon dioxide in the atmosphere since 1958. ... Carbon dioxide is an atmospheric gas comprised of one carbon and two oxygen atoms. ... The village of Suka Mauna Loa is an active shield volcano in the Hawaiian Islands, one of five volcanic peaks that together form the Island of Hawaii. ... The Facility for Airborne Atmospheric Measurements (FAAM) is a modified BAE 146 research aircraft owned jointly by the Met Office and the Natural Environment Research Council. ... For other uses, please see Satellite (disambiguation) A satellite is an object that orbits another object (known as its primary). ... European Remote-Sensing satellite (ERS) was the European Space Agencys first Earth-observing satellite. ... Categories: Stub ... LIDAR (Light Detection and Ranging; or Laser Imaging Detection and Ranging) is a technology that determines distance to an object or surface using laser pulses. ...


Lab measurements

Measuments made in the laboratory are essential to our understanding of the sources and sinks of pollutants and naturally occurring compunds. Lab studies tell us which gases react with each other and how fast they react. Measurements of interest include reactions in the gas phase, on surfaces and in water. Also of high importance is photochemistry which quantifies how quickly molecules are split apart by sunlight and what the products are plus thermodynamic data such as Henry's law coefficients. Photochemistry is the study of the interaction of light and chemicals. ... Thermodynamics (Greek: thermos = heat and dynamic = change) is the physics of energy, heat, work, entropy and the spontaneity of processes. ... In chemistry, Henrys law is one of the gas laws. ...


Modeling

In order to synthesise and test theoretical understanding of atmospheric chemistry computer models are used. Numerical models solve the differential equations governing the concentrations of chemicals in the atmosphere. They can be very simple or very complicated. One common trade off in numerical models is between the number of chemical compounds and chemical reactions modelled versus the representation of transport and mixing in the atmosphere. For example a box model might include hundreds or even thousands of chemical reactions but will only have a very crude representation of mixing in the atmosphere. In contrast 3D models represent many of the physical processes of the atmosphere but due to constraints on computer resources will have far fewer chemical reactions and compounds. Models can be used to interpret observations, test understanding of chemical reactions and predict future concentrations of chemical compounds in the atmosphere. One important current trend is for atmospheric chemistry modules to become one part of earth system models in which the links between climate, atmospheric composition and the biosphere can be studied.


References

  • Wayne, Richard P (2000). Chemistry of Atmospheres (3rd Ed.). Oxford University Press. ISBN 0-19-850375-X
  • Seinfeld, John H.; Pandis, Spyros N (1998). Atmospheric Chemistry and Physics - From Air Pollution to Climate Change. John Wiley and Sons, Inc. ISBN 0-471-17816-0

External links


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