Select the true statement about horizontal wind shear.

The correct statement about horizontal wind shear is that it reflects a change of the horizontal vector with horizontal distance, which is indeed determined by two or more anemometers located at the same height along a specific path, such as a runway. This concept is crucial, particularly in aviation, because horizontal wind shear can significantly affect aircraft performance during takeoff and landing phases.

Understanding horizontal wind shear involves recognizing that it relates specifically to variations in wind speed and direction at a consistent altitude over horizontal distances. For instance, if one anemometer shows a different wind speed or direction compared to another located along the same horizontal plane, it indicates the presence of horizontal wind shear. This phenomenon can lead to sudden changes in lift and drag on an aircraft, posing challenges for pilots during critical phases of flight.

In contrast, other options involve concepts that either refer to vertical changes or mistakenly swap the defined parameters, which do not accurately describe horizontal wind shear. This highlights the importance of correctly interpreting the specifics of each option to arrive at an accurate understanding of atmospheric wind behavior relevant to aviation safety.