Question

Why we use term modified refractive index?

Answer 1

modified refractive index

In radio engineering, the refractive indexof air on a hypothetical flat earth, given by



where z is the height above the surface, Ris the earth's radius, and n is the actual refractive index of air.


For a spherical earth with an atmospherehaving a uniform refractive index, rays are curved relative to the earth. This is approximately equivalent to a flat earth with an atmosphere in which the refractive index varies with height as z/R