Atmosphere

An atmosphere is the layer of gases surrounding a planetary body. It can extend above the surface and, on Earth, into pores in soil and rock.

Atmospheric pressure: The force per unit area exerted by atmospheric gases on a surface. The weight of overlying gas creates pressure that varies with altitude.
Radiative transfer: The transfer of energy through matter or space by electromagnetic radiation. Absorption and emission of radiation heat and cool atmospheric layers.
Weather forecasting: The prediction of future atmospheric conditions from observations and physical models. Forecasts use atmospheric measurements to estimate evolving weather.
Earth's atmosphere: The gaseous envelope surrounding Earth, composed mainly of nitrogen and oxygen. It is the familiar case, with abundant surface liquid water and life-altered composition.
Atmospheric chemistry: The study of chemical reactions and composition in planetary atmospheres. Chemical reactions determine trace gases, pollutants, and ozone abundance.
Atmospheric composition: The proportions of gases and particles in an atmosphere. Gas proportions distinguish planetary atmospheres and shape their behavior.
Greenhouse effect: The warming of a surface and lower atmosphere when gases absorb and re-emit infrared radiation. Infrared absorption by atmospheric gases raises Earth's surface temperature.
Numerical weather prediction: The use of computer simulations of atmospheric physics to predict future weather. It turns observed atmospheric states into quantitative forecasts.
Venusian atmosphere: The dense, carbon-dioxide-dominated gaseous envelope surrounding Venus. Its great pressure and heat contrast with Earth's comparatively mild surface conditions.
Ozone layer: The stratospheric region with elevated ozone concentrations that absorbs much ultraviolet radiation. Its absorption shields surface life from harmful solar ultraviolet radiation.

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