What is the effect of turbulence on aircraft performance?

The correct answer emphasizes that turbulence can indeed increase drag and disrupt the smooth flow of air over the aircraft. When an aircraft encounters turbulence, the airflow around its surface becomes chaotic. This chaotic airflow can lead to an increase in drag, as the aircraft experiences turbulent wakes and vortices that create additional resistance.

Moreover, turbulence disturbs the laminar flow, which is crucial for maintaining efficient flight. A smooth flow allows the aircraft to cut through the air with less resistance, but when turbulence intervenes, the transition to a turbulent flow can degrade overall aerodynamic efficiency. As a result, pilots need to manage their aircraft's performance during turbulent conditions, as increased drag can affect fuel consumption and overall control.

The other options do not capture the full impact turbulence has on performance. For instance, turbulence does not exclusively affect airspeed, nor does it inherently decrease lift under normal circumstances; instead, it can cause fluctuations in both lift and airspeed. Lastly, turbulence undeniably affects the aircraft’s altitude indirectly by impacting control and stability rather than having "no effect" on it.