Liinear temperature and vapor gradients are established within a short distance inside the CFDC. The aerosol flow typically represents 10% of the total flow and is placed in the center of two equal sheath flows of particle-free air in the inlet manifold. The thermal gradient modifies the parabolic laminar flow profile within the CFDC, pushing the aerosol lamina (grey shaded) toward the cold wall. The plate temperature difference and the total flow determine the position of the aerosol lamina and the steady-state conditions of temperature and relative humidity at this position. Conditions of supersaturation with respect to both ice and water are possible at all temperatures. A critical flow rate is calculated and maintained to assure that reverse thermal flow does not occur along the warm surface.