|San Francisco Bay:
In this photograph of the San Francisco Bay area taken from the International Space Station, the gray urban footprint of San Francisco, Oakland, San Jose, and their surrounding suburbs contrast strongly with the green hillsides. The brightly colored salt ponds at the northern and southern ends of the bay highlight other developments in the region. Of particular note are the Pacific Ocean water patterns that are outlined in the sun glint. Sets of internal waves traveling east impinge on the coastline south of San Francisco. At the same time, fresher bay water flows out from the bay beneath the Golden Gate Bridge, creating a large plume traveling westward. Tidal current channels suggest the tidal flow deep in the bay.
Why is this image unique?: Because the ISS orbits are not synchronous with the sun, astronauts view the Earth with variable solar illumination angles. This allows them to document phenomena such as the sun reflecting differentially off surface waters in a way that outlines complicated water structures. They can also use low sun to shadow topographic features (like the San Andreas fault, seen in this image north of the bay), and use high sun for full color information. This image was taken at just the right sun angles that all three attributes make this spectacular image.
ISS004-E-10288, 21 April 2002, 105 mm lens
The Gateway to Astronaut Photography of Earth, http://eol.jsc.nasa.gov
Robinson, J. A., B. McRay, and K. P. Lulla. 2000. Twenty-eight years of urban growth in North America quantified by analysis of photographs from Apollo, Skylab and Shuttle-Mir. In Dynamic Earth Environments: Remote Sensing Observations from Shuttle-Mir Missions. John Wiley & Sons, New York, pp. 25-42.