Golden Gate Sunset: Green Flash

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 .