A Traditional Depiction of the Global Water Cycle

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Most depicitons of the global water cycle downplay the ocean's importance
Figure 2

Salinity and Evaporation - Precipitation

In contact with both the oceans and the continents, the thin, transparent atmosphere acts as a conduit connecting the terrestrial and oceanic components of the water cycle. Figure 2 is a traditional depiction of the global water cycle as viewed by hydrologists.  It focuses on the processes of most interest to society, but gives a distorted picture of the role of the oceans. Relegating the oceans to a small corner of the diagram conveys a very inaccurate picture. In fact, the oceans cover the majority of the earth and hold 97% of the free (not chemically bound) water on the planet, comprising both the primary source of water evaporated into the atmosphere and the main site of precipitation.  We estimate that 86% of global evaporation and 78% of global precipitation occurs over the oceans.  Surely, the oceans deserve a more prominent place in any depiction of the water cycle!


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Last updated September 11, 2007
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