What defines wind shear?

Wind shear is defined as a sudden change in wind speed or direction over a relatively short distance in the atmosphere. This phenomenon is critical for aviation safety, as it can create turbulence or contribute to the development of severe weather conditions, such as thunderstorms. In practical terms, wind shear can occur at different altitudes and can vary in intensity, impacting aircraft performance during takeoff and landing.

The other options do not accurately describe wind shear. A steady wind direction indicates uniformity and stability, which contrasts with the concept of shear. A gradual change in wind patterns refers to more sustained shifts in wind characteristics, while the absence of wind signifies calm conditions, completely negating the notion of shear. Understanding wind shear is essential for recognizing its potential effects on flights and weather systems.