Elevated Ducting is described by which atmospheric scenario?

• A. Cold Air Low
• B. Warm Dry Air High
• C. Cold Moist Air Low
• D. Warm Air: High Pressure & Low Clouds

Answer: (D)

Elevated ducting happens when a warm air layer sits above a cooler, more stable air mass, creating a strong refractive-index gradient that traps radio waves between the layers and keeps them propagating at a higher level than the surface. A high‑pressure, subsiding atmosphere tends to warm and dry the air and reduce cloud formation, which fosters this kind of layered structure: warm air aloft with low clouds and a stable profile below. That combination is why the scenario described—warm air in a high‑pressure system with few clouds—best indicates an elevated duct. The other descriptions don’t as clearly reflect the warm, stable layer aloft above a cooler boundary that characterizes elevated ducting.