See Also: atmosphere(medicine)
atmosphere(dictionary)
atmosphere(encyclopedia)
atmosphere(dictionary)
Atmosphere absolute(medicine)
standard atmosphere(medicine)
ICAO standard atmosphere(medicine)

atmosphere (sh)




Gaseous envelope that surrounds the Earth.

Near the surface it has a well-defined chemical composition (see air). In addition to gases, the atmosphere contains solid and liquid particles in suspension. Scientists divide the atmosphere into five main layers: in ascending order, the troposphere (surface to 6-8 mi, or 10-13 km); the stratosphere (4-11 mi, or 6-17 km, to about 30 mi, or 50 km); the mesosphere (31-50 mi, or 50-80 km); the thermosphere (50-300 mi, or 80-480 km); and the exosphere (from 300 mi and gradually dissipating). Most of the atmosphere consists of neutral atoms and molecules, but in the ionosphere a significant fraction is electrically charged. The ionosphere begins near the top of the stratosphere but is most distinct in the thermosphere. See also ozone layer.