{ At`mos*pher"ic (&?;), At`mos*pher"ic*al (&?;), } a. [Cf. F. atmosphérique.] 1. Of or pertaining to the atmosphere; of the nature of, or resembling, the atmosphere; as, atmospheric air; the atmospheric envelope of the earth.

2. Existing in the atmosphere.

The lower atmospheric current.
Darwin.

3. Caused, or operated on, by the atmosphere; as, an atmospheric effect; an atmospheric engine.

4. Dependent on the atmosphere. [R.]

In am so atmospherical a creature.
Pope.

Atmospheric engine, a steam engine whose piston descends by the pressure of the atmosphere, when the steam which raised it is condensed within the cylinder.Tomlinson. -- Atmospheric line(Steam Engin.), the equilibrium line of an indicator card. Steam is expanded "down to the atmosphere" when its pressure is equal to that of the atmosphere. (See Indicator card.) -- Atmospheric pressure, the pressure exerted by the atmosphere, not merely downwards, but in every direction. In amounts to about 14.7 Ibs. on each square inch. -- Atmospheric railway, one in which pneumatic power, obtained from compressed air or the creation of a vacuum, is the propelling force. -- Atmospheric tides. See under Tide.