Why is the radio horizon for VHF and UHF signals more distant than the visual horizon?
Radio signals move somewhat faster than the speed of light
Radio waves are not blocked by dust particles
The atmosphere refracts radio waves slightly✓Bonne réponse
Radio waves are blocked by dust particles
Explication
The lower atmosphere is slightly denser near the ground, which bends radio waves gently downward as they travel. That refraction carries them a little past the geometric line of sight, making the radio horizon roughly 15 percent farther than the visual horizon.