  A linear analysis of baroclinic instability in a stellar radiation zone with
radial differential rotation is performed. The instability onsets at a very
small rotation inhomogeneity. There are two families of unstable disturbances
corresponding to Rossby waves and internal gravity waves. The instability is
dynamical: its growth time of several thousand rotation periods is short
compared to the stellar evolution time. A decrease in thermal conductivity
amplifies the instability. Unstable disturbances possess kinetic helicity thus
indicating the possibility of magnetic field generation by the turbulence
resulting from the instability.
