Atmospheric science is the study of the Earth's atmosphere and its various inner-working physical processes. 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. Aeronomy is the study of the upper layers of the atmosphere, where dissociation and ionization are important. Atmospheric science has been extended to the field of planetary science and the study of the atmospheres of the planets and natural satellites of the solar system.
Experimental instruments used in atmospheric science include satellites, rocketsondes, radiosondes, weather balloons, and lasers.
The term aerology (from Greek ἀήρ, aēr, "air"; and -λογία, -logia) is sometimes used as an alternative term for the study of Earth's atmosphere; in other definitions, aerology is restricted to the free atmosphere, the region above the planetary boundary layer.
Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.
Experimental instruments used in atmospheric science include satellites, rocketsondes, radiosondes, weather balloons, and lasers.
The term aerology (from Greek ἀήρ, aēr, "air"; and -λογία, -logia) is sometimes used as an alternative term for the study of Earth's atmosphere; in other definitions, aerology is restricted to the free atmosphere, the region above the planetary boundary layer.
Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.
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 is the study of motion systems of meteorological
importance, integrating observations at multiple locations and times
and theories. Common topics studied include diverse phenomena such 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 incorporate 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.
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,
each of which incorporate high levels of mathematics and physics.
Atmospheric physics 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 United Kingdom, 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.
The Earth's magnetic field and the solar wind interact with the atmosphere, creating the ionosphere, Van Allen radiation belts, telluric currents, and radiant energy.
Climatology
Regional impacts of warm ENSO episodes (El Niño).
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, physical geography, geology, geophysics, glaciology, hydrology, oceanography, and volcanology.
Atmospheres on other celestial bodies
Earth's atmosphere
All of the Solar System's planets have atmospheres. This is because
their gravity is strong enough to keep gaseous particles close to the
surface. 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.
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. Much of Mercury's atmosphere has been blasted away by the solar wind. The only moon that has retained a dense atmosphere is Titan. There is a thin atmosphere on Triton, and a trace of an atmosphere on the Moon.
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). 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.
Hot Jupiters have been shown to be losing their atmospheres into space due to stellar radiation, much like the tails of comets. These planets may have vast differences in temperature between their day and night sides which produce supersonic winds,
although the day and night sides of HD 189733b appear to have very
similar temperatures, indicating that planet's atmosphere effectively
redistributes the star's energy around the planet.
