Eff ects Animation: Flames and Smoke The movement of fl ames is governed by the movements of air currents above the fi re. The hottest part of a fi re is in the center and above this the hot air rises. As it rises it is replaced by colder air rushing inwards from the sides. This air in its turn is heated and rises, and so the process is continuous. This fl ow of air usually gives a roughly conical shape to the fl ames, with a succession of indentations representing eddies of cold air, starting at the base of the fi re and moving inwards and upwards.