The whole effect of the presence of the witches, the storm , and the description of the battle set an atmosphere of turbulence, conflict, and evil. There is an impending doom, as the King is about to order the execution of the Thane of Cawdor. The battle also foreshodows bloodshed, i.e. the violence through which Macbeth will rise to his new position, but also the violent death of the king himself.
