There are many explanations for the generation of lift found in encyclopedias, in basic physics textbooks, and on Web sites. Unfortunately, many of the explanations are misleading and incorrect. Theories on the generation of lift have become a source of great controversy and a topic for heated arguments. It is not generated by a force field , in the sense of a gravitational field ,or an electromagnetic field , where one object can affect another object without being in physical contact. It makes no difference whether the object moves through a static fluid, or the fluid moves past a static solid object.
Lift acts perpendicular to the motion.
Lift occurs when a flow of gas is turned by a solid object. The flow is turned in one direction, and the lift is generated in the opposite direction, according to Newton's Third Law of action and reaction. Because air is a gas and the molecules are free to move about, any solid surface can deflect a flow. For an airfoil , both the upper and lower surfaces contribute to the flow turning. Neglecting the upper surface's part in turning the flow leads to an incorrect theory of lift.