I have some doubts in a radio wave propagation theory. Snell's law (also known as Snell–Descartes law and the law of refraction)
1st line - ionosphera 2 nd - earth
If \$\phi_0>0\$, then the wave inclined over zenith. Is it correct? What happens if \$\phi_0<0\$?
Is the amount of ions in wave propagation important?