Figure 2-15.(A) Normal refraction, (B) Subrefraction, (C) Superrefraction, (D) Ducting.
SUPERREFRACTION. If the atmospheres
temperature increases with height (inversion) and/or
the water vapor content decreases rapidly with height,
the refractivity gradient will decrease from the
standard (table 2-1). This situation is known as
superrefraction, and causes the radar beam to deflect
earthward below its normal path (fig. 2-15, view C).
Generally, radar ranges are extended when
superrefractive conditions exist. However, some
targets may appear higher on radar than they would
Table 2-l.Refractive Conditions as a Function of N-gradient