Which type of visibility refers to conditions experienced at the surface and tower levels?

The correct answer is the one that specifically addresses the visibility conditions at both the surface and tower levels. Vertical visibility refers to how far one can see upward through the atmosphere from a certain height, mainly relevant in overcast or foggy conditions where horizontal visibility is limited.

Prevailing visibility indicates the greatest distance at which objects can be clearly seen and is typically measured in a horizontal plane, but it does not encompass levels above the surface.

Runway Visual Range (RVR) is a specific measurement related to the visibility on a runway and is crucial for pilots during takeoff and landing, providing information on how far one can see down the runway.

Therefore, the option that correctly identifies visibility conditions observed at both the surface and tower levels is "Differing level visibility." This is because it recognizes that visibility can vary at different heights due to atmospheric conditions, providing a comprehensive view of how visibility changes in a three-dimensional space. Understanding this distinction is essential for interpreting surface observations in aviation and meteorology.