  We study the screening of a homogeneous oscillating external electric field
$E_0$ in noble-gas atoms using atomic many-body calculations. At zero frequency
of the oscillations ($\omega=0$) the screened field $E(r)$ vanishes at the
nucleus, $E(0)=0$. However, the profile of the field $E(r)$ is complicated,
with the magnitude of the field exceeding the external field $E_0$ at certain
points. For $\omega >0$ the field $E(r,\omega)$ strongly depends on $\omega$
and at some points may exceed the external field $E_0$ many times. The field at
the nucleus is not totally screened and grows with $\omega$ faster than
$\omega^2$. It can even be enhanced when $\omega$ comes close to resonance with
a frequency of an atomic transition. This field interacts with CP-violating
nuclear electric dipole moments creating new opportunities for studying them.
The screening of the external field by atomic electrons may strongly suppress
(or enhance near an atomic resonance) the low energy nuclear electric dipole
transitions.
