How is turbulence defined in aviation?

Turbulence in aviation is defined as the irrational or irregular motion of air that leads to sudden and unpredictable changes in the altitude and attitude of an aircraft. This can be caused by a variety of factors, including atmospheric pressure variations, storms, jet streams, terrain, and even the wake turbulence from other aircraft.

Understanding turbulence as a disturbance in the airflow around the aircraft is critical for pilots. It is an important aspect of flight safety and performance, as it can affect how the aircraft handles during flight and may require adjustments in control inputs to maintain stability and comfort for passengers.

The other options do not accurately describe turbulence. A smooth and stable flight condition is the opposite of turbulence, while a type of weather phenomenon that improves flying conditions does not align with the nature of turbulence, which often complicates flying. Measuring airspeed does not relate to the definition of turbulence, as it’s more about assessing the aircraft's speed relative to the surrounding air rather than defining the nature of airflow disturbances.