Changes in systems can be natural or induced by humans, and many complex and far-reaching interactions can result.  This section should foster your understanding of concepts covered in the textbook specific to solutions to environmental problems as they relate to the study of systems and rates of changes, such as the planetary energy system on Earth.   

A CLOSER LOOK  - Electromagnetic Radiation

   The universe as we know it consists of two entities: matter and energy.  Matter is physical material that forms the building blocks of the physical and biological environments; energy is the ability to do work.  In summary, energy may be thought  of as a mathematical abstract quantity that is always conserved.  When energy is transformed from one form to another, it always moves from a more useful form to a less useful one.  Thus, as energy moves through a real system and is transformed from one form to another, energy is conserved but it becomes less useful.

   As part of a planetary energy system, the energy that the Earth receives from  the sun undergoes changes, affects life, oceans, atmosphere, climate, and sediments.  Nearly all the energy available at Earth's surface comes from the sun.  Although Earth intercepts only a very tiny fraction of the total energy emitted by the sun, solar energy sustains life on Earth and greatly influences climate and weather.

   Energy is emitted from the sun in the form of electromagnetic radiation (EMR).  Different forms of electromagnetic energy can be distinguished by their wavelengths.  The collection of all possible wavelengths of electromagnetic energy, considered a continuous range, is known as the electromagnetic spectrum.  The electromagnetic spectrum is one of the most important phenomena in the physical sciences, and a modest knowledge of it is fundamental to understanding many environmental topics.