Atmospheric dynamics (category)
Atmospheric chemistry (category)
Weather (category) · (portal)
Tropical cyclone (category)
Climate change (category)
Global warming (category) · (portal)
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 approach of research and draws on
environmental chemistry, physics, meteorology, computer modeling,
oceanography, geology and volcanology and other disciplines. Research
is increasingly connected with other arenas of study such as
The composition and chemistry of the
Earth's 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 changes as result of natural
processes such as volcano emissions, lightning and bombardment by
solar particles from corona. It has also 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, ozone depletion,
photochemical smog, greenhouse gases and global warming. Atmospheric
chemists seek 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
1 Atmospheric composition
3.2 Laboratory studies
4 See also
6 Further reading
7 External links
Part of the nature series
Tropical cyclone (Hurricane)
Drizzle (Freezing drizzle)
Ice pellets (Diamond dust)
Rain (Freezing rain)
Rain and snow mixed
Visualisation of composition by volume of Earth's atmosphere. Water
vapour is not included as it is highly variable. Each tiny cube (such
as the one representing krypton) has one millionth of the volume of
the entire block. Data is from
Average composition of dry atmosphere (mole fractions)
Minor constituents (mole fractions in ppm)
Carbon dioxide, CO2
Nitrous oxide, N2O
Nitrogen dioxide, NO2
typically makes up about 1%
Notes: the concentration of CO2 and CH4 vary by season and location.
The mean molecular mass of air is 28.97 g/mol.
Ozone (O3) is not
included due to its high variability.
Schematic of chemical and transport processes related to atmospheric
Greeks regarded air as one of the four elements. The first
scientific studies of atmospheric composition began in the 18th
century, as chemists such as Joseph Priestley,
Antoine Lavoisier and
Henry Cavendish made the first measurements of the composition of the
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
Christian Friedrich Schönbein in 1840.
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 by Sydney
Gordon Dobson of how the ozone layer is created and
maintained, and the explanation of photochemical smog by Arie Jan
Haagen-Smit. Further studies on ozone issues led to the 1995 Nobel
Chemistry award shared between Paul Crutzen,
Mario Molina and
Frank Sherwood Rowland.
In the 21st century the focus is now shifting again. Atmospheric
chemistry is increasingly studied as one part of the
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.
Carbon dioxide in
Earth's atmosphere if half of global-warming
emissions are not absorbed.
NASA simulation; 9 November 2015)
Nitrogen dioxide 2014 - global air quality levels
(released 14 December 2015).
Observations, lab measurements, and modeling 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.
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 (see also ongoing measurements of atmospheric CO2).
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 increasingly
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
LIDAR can provide concentration profiles of chemical compounds
and aerosol but are still restricted in the horizontal region they can
cover. Many observations are available on line in Atmospheric
Chemistry Observational Databases.
Measurements made in the laboratory are essential to our understanding
of the sources and sinks of pollutants and naturally occurring
compounds. These experiments are performed in controlled environments
that allow for the individual evaluation of specific chemical
reactions or the assessment of properties of a particular atmospheric
constituent. Types of analysis that are of interest includes both
those on gas-phase reactions, as well as heterogeneous reactions that
are relevant to the formation and growth of aerosols. Also of high
importance is the study of atmospheric photochemistry which quantifies
how the rate in which molecules are split apart by sunlight and what
resulting products are. In addition, thermodynamic data such as
Henry's law coefficients can also be obtained.
In order to synthesise and test theoretical understanding of
atmospheric chemistry, computer models (such as chemical transport
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.
Some models are constructed by automatic code generators (e.g.
Autochem or KPP). In this approach a set of constituents are chosen
and the automatic code generator will then select the reactions
involving those constituents from a set of reaction databases. Once
the reactions have been chosen the ordinary differential equations
(ODE) that describe their time evolution can be automatically
Scientific Assessment of
Tropospheric ozone depletion events
^ Zimmer, Carl (3 October 2013). "Earth's Oxygen: A Mystery Easy to
Take for Granted". New York Times. Retrieved 3 October 2013.
^ Press release on the Nobel Prize in
^ St. Fleur, Nicholas (10 November 2015). "Atmospheric Greenhouse Gas
Levels Hit Record, Report Says". New York Times. Retrieved 11 November
^ Ritter, Karl (9 November 2015). "UK: In 1st, global temps average
could be 1 degree C higher". AP News. Retrieved 11 November
^ Cole, Steve; Gray, Ellen (14 December 2015). "New
Maps Show Human Fingerprint on Global Air Quality". NASA. Retrieved 14
^ National Academies of Sciences, Engineering, and Medicine (2016).
Future of Atmospheric Research: Remembering Yesterday, Understanding
Today, Anticipating Tomorrow. Washington, DC: The National Academies
Press. p. 15. ISBN 978-0-309-44565-8. CS1 maint:
Multiple names: authors list (link)
Brasseur, Guy P.; Orlando, John J.; Tyndall, Geoffrey S. (1999).
Chemistry and Global Change. Oxford University Press.
Finlayson-Pitts, Barbara J.; Pitts, James N., Jr. (2000).
the Upper and Lower Atmosphere. Academic Press.
Seinfeld, John H.; Pandis, Spyros N. (2006). Atmospheric
Physics: From Air Pollution to
Climate Change (2nd Ed.). John Wiley
and Sons, Inc. ISBN 0-471-82857-2.
Warneck, Peter (2000).
Chemistry of the Natural
Atmosphere (2nd Ed.).
Academic Press. ISBN 0-12-735632-0.
Wayne, Richard P. (2000).
Chemistry of Atmospheres (3rd Ed.). Oxford
University Press. ISBN 0-19-850375-X.
J. V. Iribarne, H. R. Cho, Atmospheric Physics, D. Reidel Publishing
WMO Scientific Assessment of
Ozone Depletion: 2006
IGAC The International Global Atmospheric
Paul Crutzen Interview Freeview video of
Paul Crutzen Nobel Laureate
for his work on decomposition of ozone, talking to Nobel Laureate
Harry Kroto, the Vega Science Trust.
The Cambridge Atmospheric
Chemistry Database is a large constituent
observational database in a common format.
Environmental Science Published for Everybody Round the Earth
NASA-JPL Chemical Kinetics and Photochemical Data for Use in
Kinetic and photochemical data evaluated by the IUPAC Subcommittee for
Gas Kinetic Data Evaluation
Chemistry Glossary at Sam Houston State University
Calculators for use in atmospheric chemistry
An illustrated elementary assessment of the composition of air.