Why are infra-red raditions preferred over ordinary visible light for taking photo in fog?

Answer 1

The longer, stretched out waves of infra red light, unlike the short condensed waves of the visible spectrum, especially on the blue end, can more easily weave their way through the water droplets that form fog. The tighter waves of the visible spectrum present a larger front which collides with the tiny water droplets and are reflected away, so they do not penetrate. Therefore we cannot see through fog lit by "normal" light, whereas the long, stretched out infra red waves penetrate the fog more easily, enabling us to "see through" it