What is 'dihedral angle' and how does it affect flight?

The concept of 'dihedral angle' refers specifically to the upward angle of the wings relative to the horizontal plane. This design feature plays a critical role in enhancing the aircraft's roll stability. When an aircraft with a positive dihedral angle experiences a disturbance, such as a gust of wind, the inclination of the wings helps to naturally return the aircraft to level flight.

As the aircraft rolls to one side, the wing that is lower experiences a higher angle of attack due to the dip, which increases lift on that wing. Conversely, the wing that is higher will have a lower angle of attack and consequently generate less lift. This differential lift works to counteract the roll, helping the aircraft stabilize and maintain level flight. This inherent stability is crucial for pilot control and overall safety, making the dihedral angle a significant aspect of aircraft design.

In contrast, the other choices relate to different aerodynamic concepts that do not pertain to the specific definition and function of dihedral angle in enhancing roll stability.