Is foggy weather a geographical phenomenon or a physical phenomenon?

Foggy weather should be considered as a physical phenomenon.

The formation of fog requires not only water vapor, but also condensation nuclei. Suspended particles such as automobile exhaust, dust and industrial waste gas in cities are "accomplices" of fog, which just provide condensation nuclei suitable for water vapor accumulation. Moreover, the more condensation nuclei, the easier it is to prolong the fogging time and increase the fog concentration.

Of course, fog has something to do with geography, and some specific geographical environments are more likely to form fog.