what is dynamic lift?

Dynamic lift also known as aerodynamic lift is a phenomenon where an airfoil (wing of a airplane or blade) experiences a upward thrust when moving in a fluid.

The lift is there because of difference in pressures created by the movement of air in different velocities along the upper and lower surfaces of the airfoil.  When the airfoil moves forward with a velocity, the stream of air passing through its lower surface attains higher velocity because of the shorter distance it has to cover while the air passing through the upper surface has a higher velocity. From Bernoulli’s theorem we know that higher is the velocity lower becomes the pressure and vice versa. Thus the airfoil in motion has low pressure on its upper surface and high pressure in its lower surface. This gives the foil a lift.