As the distance from the ball increases, the speed of the air changes, so that the airflow around the ball exhibits the patterns shown in the figure below. If the ball is spinning clockwise as seen in the diagram, the air flows faster over the top of the ball. The pressure on the top is lower than the pressure on the bottom of the ball, and there is a net lift force on the ball towards the top of the diagram. This force is called the Magnus Force . The lift force does not have to point upwards.
Turbulent regions can also form.
The wake behind the ball can be deflected because the spinning surface pulls air with it. This again can result in a net lift force. This force is called the wake deflection force . For an airplane wing, the lift force depends on the shape of the wing and on the angle of attack. Shapes that produce more lift also produce more drag.