Natural Systems

At the beginning of this chapter we defined a system as a collection of interacting objects. The Earth and its atmosphere defines the Earth system. A system consists of three basic elements: (1) a functioning set of components, (2) a flow of energy which powers them, and (3) a process for the internal regulation of their functioning called feedback (Trewartha, et. al., 1977). 

Components of the Earth System

The Earth system is a complex functioning system  that includes all the components of the various "spheres" like the solid Earth or lithosphere, the gaseous envelope surrounding the Earth that is the atmosphere, biosphere comprised of all living organisms and the hydrosphere or "water sphere".

Figure 2.21 The Earth System (after Christopherson, 2005)

The Earth system diagram shows arrows representing flows of energy and mass that connect and intertwine the four spheres. At the top, solar energy drives many of the environmental processes operating in the  four spheres. The Earth's internal heat engine and the gravitational attraction of the moon are additional sources of energy to power Earth systems. There is a constant cycling of energy and mass between the hydrosphere, lithosphere, atmosphere, and biosphere as indicated by the arrows.

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