Atmospheric sciences

"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. Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather forecasting. Climatology is the study of atmospheric changes (both long and short-term) that define average climates and their change over time, due to both natural and anthropogenic climate variability. Atmospheric science has been extended to the field of planetary science and the study of the atmospheres of the planets of the solar system.

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.

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.

Atmospheric dynamics

Atmospheric dynamics involves the study of observations and theory dealing with all motion systems of meteorological importance. The list includes diverse phenomena as thunderstorms, tornadoes, gravity waves, tropical cyclones, extratropical cyclones, jet streams, and global-scale circulations. The goal of dynamical studies is to explain the observed circulations on the basis of fundamental principles from physics. The objectives of such studies include improving weather forecasting, developing methods for predicting seasonal and interannual climate fluctuations, and understanding the implications of human-induced perturbations (e.g., increased carbon dioxide concentrations or depletion of the ozone layer) on the global climate. [University of Washington. [http://www.atmos.washington.edu/academic/atmosdyn.html Atmospheric Dynamics.] Retrieved on 2007-06-01.]

Atmospheric physics

Atmospheric physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chemical models, radiation balancing, and energy transfer processes in the atmosphere and underlying oceans. In order to model weather systems, atmospheric physicists employ elements of scattering theory, wave propagation models, cloud physics, statistical mechanics and spatial statistics which are highly mathematical and related to physics. It has close links to meteorology and climatology and also covers the design and construction of instruments for studying the atmosphere and the interpretation of the data they provide, including remote sensing instruments.

In the UK, atmospheric studies are underpinned by the Meteorological Office. Divisions of the U.S. National Oceanic and Atmospheric Administration (NOAA) oversee research projects and weather modeling involving atmospheric physics. The U.S. National Astronomy and Ionosphere Center also carries out studies of the high atmosphere.

Climatology

In contrast to meteorology, which studies short term weather systems lasting up to a few weeks, climatology studies the frequency and trends of those systems. It studies the periodicity of weather events over years to millennia, as well as changes in long-term average weather patterns, in relation to atmospheric conditions. Climatologists, those who practice climatology, study both the nature of climates - local, regional or global - and the natural or human-induced factors that cause climates to change. Climatology considers the past and can help predict future climate change.

Phenomena of climatological interest include the atmospheric boundary layer, circulation patterns, heat transfer (radiative, convective and latent), interactions between the atmosphere and the oceans and land surface (particularly vegetation, land use and topography), and the chemical and physical composition of the atmosphere. Related disciplines include astrophysics, atmospheric physics, chemistry, ecology, geology, geophysics, glaciology, hydrology, oceanography, and volcanology.

Atmospheres on other planets

All of the Solar System planets have atmospheres as their large masses mean gravity is strong enough to keep gaseous particles close to the surface. The larger gas giants are massive enough to keep large amounts of the light gases hydrogen and helium close by, while the smaller planets lose these gases into space. [cite journal|last=Sheppard|first=Scott S.|coauthors=Jewitt, David; Kleyna, Jan|title=An Ultradeep Survey for Irregular Satellites of Uranus: Limits to Completeness|journal=The Astronomical Journal| volume=129|pages=518–525 | year=2005| doi=10.1086/426329 | id=arxiv|astro-ph|0410059v1] The composition of the Earth's atmosphere is different from the other planets because the various life processes that have transpired on the planet have introduced free molecular oxygen.cite book | last=Zeilik | first=Michael A. | coauthors=Gregory, Stephan A. | title=Introductory Astronomy & Astrophysics | edition=4th ed. | year=1998 | publisher=Saunders College Publishing | isbn=0030062284 | pages=67 ] The only solar planet without a true atmosphere is Mercury which had it mostly, although not entirely, blasted away by the solar wind. [Hunten D. M., Shemansky D. E., Morgan T. H. (1988), "The Mercury atmosphere", In: Mercury (A89-43751 19-91). University of Arizona Press, pp. 562–612]

Planetary atmospheres are affected by the varying degrees of energy received from either the Sun or their interiors, leading to the formation of dynamic weather systems such as hurricanes, (on Earth), planet-wide dust storms (on Mars), an Earth-sized anticyclone on Jupiter (called the Great Red Spot), and holes in the atmosphere (on Neptune).cite web | last=Harvey | first=Samantha | date=2006-05-01 | url=http://solarsystem.nasa.gov/scitech/display.cfm?ST_ID=725 | title=Weather, Weather, Everywhere? | publisher=NASA | accessdate=2007-09-09 ] At least one extrasolar planet, HD 189733 b, has been claimed to possess such a weather system, similar to the Great Red Spot but twice as large.cite journal | last=Knutson | first=Heather A. | coauthors=Charbonneau, David; Allen, Lori E.; Fortney, Jonathan J. | title=A map of the day-night contrast of the extrasolar planet HD 189733b | journal=Nature | year=2007 | volume=447 | pages=183 | doi=10.1038/nature05782 (Related [http://www.cfa.harvard.edu/press/2007/pr200713.html press release] )]

Hot Jupiters have been shown to be losing their atmospheres into space due to stellar radiation, much like the tails of comets. [cite web | author=Weaver, D.; Villard, R. | url=http://hubblesite.org/newscenter/archive/releases/2007/07/full/ | title=Hubble Probes Layer-cake Structure of Alien World's Atmosphere | work=University of Arizona, Lunar and Planetary Laboratory (Press Release) | date=2007-01-31 | accessdate=2007-08-15] [cite journal | journal=Nature | last=Ballester | first=Gilda E. | coauthors=Sing, David K.; Herbert, Floyd | title=The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b | volume=445 | pages=511 | year=2007 | doi=10.1038/nature05525] These planets may have vast differences in temperature between their day and night sides which produce supersonic winds, [cite journal | last=Harrington | first=Jason | coauthors=Hansen, Brad M.; Luszcz, Statia H.; Seager, Sara | title=The phase-dependent infrared brightness of the extrasolar planet Andromeda b | journal=Science | volume=314 | pages=623 | year=2006 | doi=10.1126/science.1133904 | pmid=17038587 (Related [http://www.nasa.gov/vision/universe/starsgalaxies/spitzer-20061012.html press release] )] although the day and night sides of HD 189733b appear to have very similar temperatures, indicating that that planet's atmosphere effectively redistributes the star's energy around the planet.

References

External links

* [http://www.stuffintheair.com/chasing-storms.html Atmospheric fluid dynamics applied to weather maps] - Principles such as Advection, Deformation and Vorticity