What is the definition of the angle of attack?

The angle of attack is defined as the angle between the wing's chord line and the relative wind. This measurement is crucial in aerodynamics because it directly affects the lift generated by the wing. As the angle of attack increases, the airflow over the wing changes, affecting its lift characteristics.

When the angle of attack is optimal, it produces the maximum amount of lift without leading to a stall, which occurs when the airflow separates from the wing's upper surface. Understanding the relationship between angle of attack and lift is fundamental for pilots, as it helps in managing the aircraft's performance during different phases of flight.

Other definitions presented in the options relate to different concepts. For instance, the angle between the wing and the horizon pertains to the aircraft's attitude rather than the aerodynamics of lift production. Similarly, the angle between the aircraft nose and the flight path relates to the performance and trajectory of the aircraft rather than the wing's interaction with the air. Lastly, the angle of descent during an approach is specifically tied to landing techniques and not directly to the aerodynamics of lift from the wings. Thus, the correct definition focuses specifically on how the wing interacts with the air to produce lift.