Publisher's Synopsis
The image of the Earth on the front cover was acquired from the GOES–8 Imager by the Laboratory for Atmosphere at NASA′S Goddard Space Flight Center, Greenbelt, MD. It was taken on September 2, 1994, using two channels for the Imager to produce a "natural color" effect. The photos shown here on the back cover illustrate the four spheres of the Earth system – the atmosphere, biosphere, hydrosphere, geosphere – together with changes being produced by human activities.
