Explanation:
The setting is San Francisco Bay, the time is sunset, and the bridge is the
Golden Gate.
What you are about
to see
is an unexpected double sunset ending with a rare
green flash.
Watch closely -- in the recorded time-lapse
sequence,
unusually warm air created by bridge traffic refracts sunlight toward the Earth,
causing a superior image of the top of the Sun to form.
This image will disappear -- marking the first "sunset" -- only after the main image
has dipped below the deck.
All the while,
boats pass in the foreground, cars pass over the bridge, and clouds
reflecting sunlight drift by in the distance.
The scene ends with Earth's turbulent
atmosphere
itself creating a path that only
higher-energy
visible
sunlight can traverse, making the last glimpse of our home star appear to
flash green.
