Bernoulli's Principle

Explanation

The wings of an airplane (aerofoil) are so designed that its upper surface is more curved than the lower surface and the front edge is broader than the real edge. As the aircraft moves, the air moves faster above the aerofoil than at the bottom as shown in Figure.
According to Bernoulli's Principle, the pressure of air below is greater than above, that creates an upthrut called the dynamic lift to the aircraft.