  The sustained intense experimental activity around atomic spectroscopy and
the resulting high-precision measurements of atomic spectral lines attract
interest in Lamb shift as a witness for noninertial effects in quantum systems.
We investigate the Lamb shift in a two-level system undergoing uniform circular
motion and coupled to a quantum electromagnetic field inside a cavity. We show
that when the separation between different cavity modes is large compared to
the width of each cavity mode, both the inertial and noninertial contributions
to the Lamb shift are convergent. In addition, we find that the
purely-noninertial Lamb shift maximizes away from the atomic resonance by an
amount decided by the angular frequency of the circulating atom, lending itself
to efficient enhancement by a suitable tuning of the cavity parameters. We
argue that the noninertial contribution becomes detectable at accelerations
$\sim 10^{14}~\mathrm{m/s^2}$.
