What effect does airflow across an airfoil have on lift?

The correct answer focuses on how lift is generated through pressure differences that result from the airflow disruption around an airfoil. When air flows over and under an airfoil, it moves at different speeds across the two surfaces due to the shape of the airfoil. According to Bernoulli's principle, this difference in speed results in a pressure difference: faster-moving air over the top surface generates lower pressure, while slower-moving air beneath the airfoil maintains higher pressure. This pressure difference between the upper and lower surfaces creates an upward lifting force, enabling the aircraft to ascend or maintain altitude.

Other options misrepresent the nature of lift generation. One suggests that both surfaces experience equal airflow, which overlooks the essential principle of varying speeds leading to pressure differences. Another states that lift is created solely by the upper surface, neglecting the crucial role that both surfaces play in lift generation due to their interaction with airflow. Lastly, the notion that lift is unaffected by airflow patterns contradicts fundamental aerodynamic principles, as airflow is key to establishing the varying pressures necessary for lift.