Distant Urban Sky Glow
The glow of the Miami metro area, over 50 miles away across eastern Florida bay, penetrates a swath of night sky in the middle Keys, and reflects off the shallow and tranquil waters. Some refer to man-made sky glow as a form of light pollution. Millions of light sources all across the big population center produce this effect in aggregate, which in turn scatters through the atmosphere and relects off high clouds. The tan tone arises mainly from sodium vapor lamps used for streetlights. Thirty or more years ago, when somewhat dimmer and more bluish mercury vapor bulbs were the lighting of choice for streets, this glow would have been more monochromatically gray-white, and of course dimmer, given fewer people and smaller area of urbanized land. I have lived just long enough to see the evolution of sky glow from gray to orange, and of course brighter, near urban areas. "Near" is getting farther away, too.
1 ESE Fiesta Key FL (5 Dec 8), looking NNE.