Cubdriver

Maybe you are a little fuzzy on what happens around an airfoil in a fluid flow. If you're asking why does it suddenly quit lifting, be aware that visualizing airflow is not especially easy. Smoke streams are used to help illustrate the flow around an airfoil, which is a 2-D "slice" of a wing. Generally, at less than critical AOA's the smoke will work its way around the airfoil on both sides, top and bottom, and since the distance around the top is longer, regardless of any camber present, it has to speed up to get around the airfoil and meet the other half of the airflow that went around the bottom of the airfoil. It is a law of aerodynamics called the Kutta Condition these two smoke trails must meet at the back of the airfoil. The speeding up of the smoke on the top causes a drop in pressure by Bernoullis Law. This is where the lift comes from. When the critical AOA is finally reached around 12-16 degrees (it varies for different cambers), the amount of speeding up the smoke on the top has to do to meet the flow from the bottom is so much that it can no longer do so without flying off the surface of the airfoil. It becomes turbulent flow, and this is the stalled condition. For the time being, ignore the lift from reactionary forces where the air bounces off the bottom of the wing, and lift from reactionary forces from air being thrown off the back of the airfoil in a downwash. The basic principle is that the air cannot stay attached to the airfoil when the distance gets to be too high. It's that simple. And the reason airfoils are studied is they represent the most basic, 2-dimensional flow situation. You can see the same behavior in 3 dimensions by attaching yarn tufts to a wing and observing them flip around, but it gets a lot more complicated because some of the wing may not stall, some of the wing will be affected by the open sides of the wing, some of the wing will have a different camber, and it is harder to observe effects related to the stall. Does this help or is another aspect unclear? Richard Shevell's Fundamentals of Flight Second Edition is a useful reference work if you need more than the FAA or Jeppeson have on the subject.