Silicon Valley Double Illumination...
Exotic cloud formations over San Francisco Bay, painted by a setting sun as the lights begin to come on in a darkening Silicon Valley. The lights yellow hue is due to the use of Low Pressure Sodium ( LPS ) bulbs, which enhance the star gazing capability of the astronomers at the nearby Lick Observatory on Mount Hamilton.
( http://mthamilton.ucolick.org//public/lighting/Summary2.html )
