Convection in a rotating layer with nearly insulating boundaries

Finite amplitude steady convection in a horizontal layer of fluid heated from below with nearly insulating boundaries and rotating about a vertical axis is investigated. The main result is that the only steady stable convective motion in the form of square pattern becomes unstable once the rotation parameter τ exceeds the value 7.45. The disturbances which have the highest growth rates are in the form of rolls inclined at an angle of 45° to the basic wave vectors of the steady motion.