Special attention in the role of convection in vapor crystal growth has been paid since some single crystals under high gravity acceleration of $10g_0$ appear considerably larger than those under normal gravity acceleration ($1g_0$). With increasing the gravity acceleration from $1g_0$ up to $10g_0$, the total molar flux for ${Delta}T$ = 30 K increases by a factor of 4, while for ${Delta}T$ = 90, by a factor of 3. The maximum molar fluxes for three different gravity levels of $1g_0$, $4g_0$ and $10g_0$, appear approximately in the neighborhood of y = 0.5 cm, and the molar fluxes show asymmetrical patterns, which indicate the occurrence of either one single or more than one convective cell. As the gravitational level is enhanced form $1g_0$ up to $10g_0$, the intensity of convection is increased significantly through the maximum molar fluxes for ${Delta}T$ = 30 K and 90 K. At $10g_0$, the maximum total molar flux is nearly invariant for for ${Delta}T$ = 30 K and 90 K. The total molar flux increases with increasing the gravity acceleration, for $1g_0{leq}g_y{leq}10g_0$, and decreases with increasing the partial pressure of component B, a noble gas called as Kr (Krypton), $P_B$. The ${{mid}U{mid}}_{max}$ is directly proportional to the gravity acceleration for 20 Torr $P_B{leq}300$ Torr. As the partial pressure of $P_B$ (Torr) decreases from 300 Torr to 20 Torr, the slopes of the ${{mid}U{mid}}_{max}s$ versus the gravity accelerations increase from 0.29 sec to 0.54 sec, i.e. by a factor of 2. The total molar flux of $Hg_2Cl_2$ is first order exponentially decayed with increasing the partial pressure of component B, $P_B$ (Torr) from 20 Torr up to 300 Torr.