How is moderate turbulence defined?

Moderate turbulence is characterized by its ability to create oscillations that are felt by occupants but still allows the pilot to maintain positive control of the aircraft. The turbulence is indeed more intense than light turbulence, which means the aircraft may experience noticeable changes in altitude and attitude, but these movements are typically manageable. Pilots can expect to see rapid changes in airspeed and slight increases in the difficulty of flight control, but this does not impede their ability to fly the aircraft safely.

The other options present scenarios that either exaggerate the effects of turbulence or do not relate to the definition of turbulence at all. For instance, severe turbulence would be defined by extreme erratic movements, which goes beyond what is typical for moderate turbulence. Additionally, the decision to refrain from serving food during a flight is not related to turbulence and does not contribute to understanding its definition. Thus, the definition of moderate turbulence emphasizes that while it may present challenges, full control of the aircraft remains achievable.