Atmosphere Hydrosphere E98 Anthrosphere ergy Geosphere Nutrients, organic matter Figure 1. 1. Illustration of the close relationships among the air, water, and earth environments with each other and with living systems, as well as the tie-in with technology(the anthrosphere) Traditionally, environmental science has been divided among the study of the atmosphere, the hydrosphere, the geosphere, and the biosphere. The atmosphere is the thin layer of gases that cover Earths surface. In addition to its role as a reservoir of gases, the atmosphere moderates Earths temperature, absorbs energy and damag ing ultraviolet radiation from the sun, transports energy away from equatorial regions, and serves as a pathway for vapor-phase movement of water in the hydro logic cycle. The hydrosphere contains Earths water. Over 97% of Earths water is in oceans, and most of the remaining fresh water is in the form of ice. Therefore only a relatively small percentage of the total water on Earth is actually involved with terrestrial, atmospheric, and biological processes. Exclusive of seawater, the water that circulates through environmental processes and cycles occurs in the atmosphere, underground as groundwater, and as surface water in streams, rivers lakes, ponds, and reservoirs. The geosphere consists of the solid earth, including soil, which supports most plant life. The part of the geosphere that is directly involved with environmental processes through contact with the atmosphere, the C 2000 CRC Press LlCFigure 1.1. Illustration of the close relationships among the air, water, and earth environments with each other and with living systems, as well as the tie-in with technology (the anthrosphere). Traditionally, environmental science has been divided among the study of the atmosphere, the hydrosphere, the geosphere, and the biosphere. The atmosphere is the thin layer of gases that cover Earth’s surface. In addition to its role as a reservoir of gases, the atmosphere moderates Earth’s temperature, absorbs energy and damag￾ing ultraviolet radiation from the sun, transports energy away from equatorial regions, and serves as a pathway for vapor-phase movement of water in the hydro￾logic cycle. The hydrosphere contains Earth’s water. Over 97% of Earth’s water is in oceans, and most of the remaining fresh water is in the form of ice. Therefore, only a relatively small percentage of the total water on Earth is actually involved with terrestrial, atmospheric, and biological processes. Exclusive of seawater, the water that circulates through environmental processes and cycles occurs in the atmosphere, underground as groundwater, and as surface water in streams, rivers, lakes, ponds, and reservoirs. The geosphere consists of the solid earth, including soil, which supports most plant life. The part of the geosphere that is directly involved with environmental processes through contact with the atmosphere, the © 2000 CRC Press LLC