Turbulence
Turbulence increases as the flat surface area exposed to the oncoming air flow increases
 Vehicles travelling fast through the air must try to minimise the disruption to the air flow passing over their surface. They do this by adopting aerodynamic shapes. Shapes that allow the air to pass smoothly over their surface. As air becomes increasingly turbulent, while moving over objects, so does the force of drag increase. As drag increases the velocity of the vehicle decreases.
But if the wing's angle, at which it approaches the oncoming airflow, increases, turbulence generated on top of the wing, destroys the force of lift. TUrbulence is created as the angle of the wing increases