Heading east from San Francisco on the Bay's unglamorous span to Oakland involves driving through what feels like a dark tunnel. The top deck, running into San Francisco, has all the views. The under side, the lower deck, is enclosed, cave-like.
Winter means rain, sometimes dense rain.
Under the joints of the upper sections, water cascades on cars below. It can be hard to see.
The center of the bridge is an actual tunnel through Yerba Buena Island, a large rock that was there long before the bridge. There's less rain in the tunnel, but distorting light, even at midday.