Growing up in San Francisco, fog was a daily occurrence. I gained a deeper appreciation for the coolness of fog, the protection it provides from intense sun and heat, until I moved to SoCal.
From the perspective of lighting, I think that daytime fog is especially cool. Daytime fog can be bright, but from where the light comes is indeterminate. In daytime fog, light feels simultaneously omnipresent and nonexistent. As much can be said for the presence - or lack thereof - of shadows; they are at once everywhere and nowhere.
Some folks think that fog is depressing and hides that which we can see, which is sometimes true. However, I also think that fog can soften and round that which we experience, which can be a source of comfort or relief for those of us who experience social anxiety or mental overstimulation.






