of the self-similar solutions, and they suggested that the condensing layer will fragment in various scales as long as the transverse scale is larger than the Field length. Physics of the bistable fluid has been investigated by many authors. @ZP69 [hereafter ZP69] and @PB70 investigated the structure of the transition front connecting the CNM and WNM under the plane-parallel geometry. The thickness of the transition front is characterized by the Field length below which the TI is stabilized by heat conduction [@F65]. They found that a static solution is obtained at a so-called saturation pressure. The transition front becomes a condensation (evaporation) front if surrounding pressure is larger (less) than the saturation pressure. These properties of the transition front depend on its geometry. In the spherical symmetric geometry, @GL73 investigated isobaric flows. They found that spherical clouds have a minimum size below which they inevitably evaporate [more general description is found in @Netal05]. Linear stability of the transition layers has been investigated by @IIK06 in the plane-parallel geometry, and they found that the evaporation front is unstable against corrugation type fluctuation, while the condensation front is stable. @SZ09 have considered the effect of magnetic field on the instability. The physical 