On an apparently sunny day, as a bicycle rode along the Embarcadero, fog could be seen performing its usual magic by making the Bay Bridge vanish.

A bicycle ride along San Francisco's The Embarcadero ended at Rincon Park. A bench provided a good place to huddle on that chilly morning. Perhaps brunch was being discussed, with its promise of aromatic coffee and Eggs Benedict.

Near noon on a Sunday morning in late winter, the ocean fog had still not burned off. It was still so thick that the city had become invisible behind the park. The muffling nature of fog, combined with Sunday's lack of traffic, created a quiet morning.

The airplane rose above the fog