1. The problem statement, all variables and given/known data This is from a old exam Humid air has a different refractive index than dry air: in the microwave region n'(dry) > n'(humid) and n''(dry) < n''(humid), where n' and n'' denote the real and imaginary part of the refractive index, respectively. How are the effects asked for above different (qualitatively) on dry and humid days ? 2. Relevant equations n =c/v 3. The attempt at a solution What are they asking for ? It is how the < changes during dry/humid days ?