What does "skin effect" refer to in radar speed detection?

The term "skin effect" in radar speed detection relates to the phenomenon where radar signals may not accurately represent the speed of vehicles that are closely together. When multiple vehicles are in close proximity, the radar system can struggle to isolate the speed of a single vehicle, leading to difficulties in providing an accurate reading. This effect can cause the radar to register erroneous speed data because the signals bounce off multiple vehicles, creating confusion in the radar's ability to track individual speeds.

In contrast, the other options do not accurately describe the skin effect. The ability of radar to penetrate obstacles pertains to the limitations and capabilities of radar technology rather than its interaction with vehicle speed. The surrounding environment's influence on radar signals relates more to interference caused by various physical barriers or weather conditions rather than the direct issue of vehicles being too close together. Lastly, the variation in vehicle speed due to road conditions speaks to how different surfaces or environmental factors can change a vehicle's speed but does not tie into the concept of the skin effect itself.