"Atmosphere" is composed from the greek expressions "Atmos" = dust, fog and "spharia" = sphere. Therefore in its historic sense it concerns the gaseous hull around the earth

In its contemporary interpretation the word Atmosphere may concern:

1. The gaseous hull around the globe in its typical consistency: 

  • 78 % N2
  • 21 % O2
  • 0,9 % Ar
  • 0,03 % CO2
  • small fractions of various other gases
  • Variable fraction of gaseous water from 0 to 40 gramms per kg of air.
  • "Atmospheric pressure" is the designation for the air pressure in normal conditions on ground level. On sea level the atmospheric pressure is around 1000 hectopascal [hPa], varying +/- 50 hPa depending on meteorological conditions. 1 Pascal [Pa] = 1 N/m².

2. Many other objects in the universe also have gaseous hulls. Those are also designated "Atmosphere", but the consistence of all extraterestric Atmospheres known to date is very much different from the Atmosphere of the earth.

3. "Atmosphere" may also designate the gaseous conditions around a chemical or physical process. Within a closed volume such an Atmosphere may be of completely different consistency than the Atmosphere of the earth. In pressure chambers or vacuum chambers the pressure of a technical atmosphere may be 10-15 up to many 1000 times the pressure of the natural Atmosphere. 

In a Low Pressure Plasma the Atmosphere may be composed of any mixture of any existing gases and even many substances which are liquid under normal atmospheric conditions are gaseous in Low Pressure.