atmosphere جو، هواسپهر javv (#), havâsepehr Fr.: atmosphère The gaseous envelope surrounding a star, planet, or moon.
Several solar system planets
retain considerable atmospheres, due to their strong
gravitational force. The gas motions in the planetary
atmosphere, as a response to the heating, coupled with the rotation
forces, generate the meteorological systems. The planetary satellites
→ Titan and → Triton
also have atmospheres (M.S.: SDE).
A unit of pressure, called standard atmosphere, which is the pressure of
air balanced by a column of mercury 76 cm high with a density of the mercury of
13.595 g/cm3 at normal acceleration of gravity. Such a column applies a
pressure equal to its weight to each square cm, or
1.01325 x 106 dynes/cm2 = 1.01325 x 105
N/m2. Since this pressure is equal to 1.03323 kilograms of force per square centimeter,
instead of it use is often made of the technical atmosphere (at),
exactly equal to 1 kgf/cm2.
Etymology (EN): New L. atmosphaera, from Gk. atmos “vapor” +
spharia “sphere.” Etymology (PE): Havâsepehr, from Mod.Pers. havâ, → air, +
sepehr, → sphere.
Javv “air, atmosphere,” from Ar. jauw. |
