A great challenge in simulating dendritic crystal growth from various supercoolings is the large difference in time and length scales. Dendrite growth is also known to be affected by natural convection. By using adaptive mesh refinement and rescaling, the effects of gravity and its orientation on tip growth rate and dendrite morphology are investigated. Our simulation results are consistent with previous theories and experimental observations. (C) 2009 Elsevier B.V. All rights reserved.