What happens during ducting?
Ducting is exceptional super-refraction. Super-refraction occurs when the trajectory of a radar beam bends towards the earth’s surface more than normal. In other words, the rate the elevation of the radar beam changes with distance away from the radar is less than normal. The radar beam will tend to increase in height above the earth’s surface when moving away from the radar site because of the earth’s curvature. In a super-refraction situation, the radar beam could be increasing at a lesser rate with height than normal as the beam moves away from the radar site or the beam could even be bending back down and getting closer to the earth’s surface in spite of the earth’s curvature. It is ducting when the radar beam actually bends closer the earth’s surface with distance away from the radar. The bending could be strong enough for the radar beam to bounce off the earth’s surface.
