  The atmospherical pressure gradients of spherical celestial bodies are very
important in astrophysics and other related areas. The classical form of the
gradient in a gravitation-dominated celestial body:
$\frac{dp}{dR}=-\frac{GM}{R^2}\rho$ has been widely adopted for quit a long
time. But, in this form, a factor has been neglected: the centrifugal force
that due to the thermal motion of gaseous particles in a centripetal force
field. The pressure gradient is actually caused by the ``effective weight''
$f_g^{^{\prime}}$ of gaseous particles but not by their real gravity $f_g$. For
this reason, a modified form of the pressure gradient is given in this paper.
Though the changes are very small in most celestial bodies, they may be not
negligible in theories of stars, accretion disks, and so on with a cumulative
effect.
