Earth Observations taken during Expedition Four

ISS004-E-10288 (21 April 2002) --- This view featuring the San Francisco Bay Area was photographed by an Expedition 4 crewmember onboard the International Space Station (ISS). The gray urban footprint of San Francisco, Oakland, San Jose, and their surrounding suburbs contrasts strongly with the green hillsides. Of particular note are the Pacific Ocean water patterns that are highlighted 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. Because the ISS orbits are not synchronous with the sun, station crewmembers view 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.