Which causes of spectrum width are most likely to be functions of range?

The correct answer focuses on factors impacting spectrum width as a function of range, which typically reflects changes in the environment or the observed phenomena as the distance from the radar increases.

Wind shear refers to variations in wind speed or direction with altitude. As radar beams extend into the atmosphere, changes in the wind can lead to varying levels of turbulence and Doppler shifts, which affect spectrum width. These variations are often more pronounced at greater distances due to the cumulative effects of changing wind patterns.

The difference in hydrometeor sizes affects scattering and the return signal's Doppler spectrum characteristics. As the radar beam travels further into the atmosphere, it can encounter a diversity of hydrometeor types and sizes that lead to changes in how the radar detects particles, contributing to variations in spectrum width.

Rotation rate pertains to the spinning motion of the earth or a storm system, which can also influence how signals are received and interpreted by the radar at different ranges. It can create a dynamic environment where Doppler shifts from rotating objects become more pronounced as you move away from the radar due to the changing perspective of the rotating motion.

Together, these three elements—wind shear, differences in hydrometeor sizes, and rotation rate—combine to create functions of spectrum width that vary with range