Abstract
This paper employs continuum theory to examine the onset of a particular type of cellular thermal convection when a long pitch cholesteric liquid crystal between two infinite horizontal flat plates is subject to a vertical temperature gradient. The initial alignment considered is uniform and either perpendicular or parallel to the plane of the plates. A Fourier series method is used to investigate the influence of the pitch of the cholesteric on the critical threshold gradient at which each of the initial alignments becomes unstable.