The Interconnected Spheres of the Earth
The Earth is certainly a fascinating place. There is no other planet like this truly unique and one of a kind object. Our knowledge of its inner workings and the systems that function within it continue to grow with each passing day. But as things usually occur, the more answers we uncover, the more questions we have. One of the greatest and most intriguing things about this planet is its interconnected spheres (or systems). These spheres describe all of the many great things that make this planet habitable. It's through a study of these interconnected and related spheres that we can begin to truly understand our impacts to the Earth and the environment. This will give us a "big picture view" of how the natural processes and cycles of Earth work (similar to a Life Cycle Assessment for a product) and how human activity is changing them. The first concept to learn in Earth Systems Science is the six main spheres of the planet.
Atmosphere – This is the gaseous layer of air that encloses the Earth. Air is a mixture of gases made mostly of nitrogen (78.08%), oxygen (20.95%, Argon (0.93%), and carbon dioxide (0.033%). The atmosphere allows water to be transferred between the other spheres as part of the Hydrologic Cycle. The atmosphere is subdivided into 5 smaller spheres.
The troposphere is the bottom most layer of the atmosphere. This layer is defined by the fact that all weather, such as precipitation, occurs here. We live in the troposphere.
The next layer of the atmosphere is the stratosphere. This is where most of our commercial airplanes fly. It extends from a height of about 5 to 10 miles above Earth’s surface (varies with temperature and location) to a maximum vertical height of 31 miles. This is also where our Ozone layer is.
The third layer of the atmosphere is the mesosphere. This layer extends from 31 miles upward to about 53 miles upward. It is here where most meteorites burn up.
The fourth layer of the atmosphere is the thermosphere. This layer extends from about 53 miles upward to somewhere between 311 and 621 miles into space. It is in the layer that the space shuttle would orbit the planet. The start of “space” also begins here at a vertical height of 62 miles above Earth’s surface.
The fifth and final layer of the atmosphere is the exosphere. This part of the atmosphere is where atoms and molecules begin to drift freely. They are far enough away from Earth to resist its pull of gravity.
Hydrosphere – The hydrosphere is the interconnected system of all of the liquid water on this planet. The process of the hydrologic cycle such as evapotranspiration, precipitation, and groundwater transport are all a part of the hydrosphere. Humans have become a large part of the hydrosphere too. We consume large quantities of water that has huge impacts on how this system works. Water is stored in oceans, lakes, streams, and rivers.
Lithosphere - The lithosphere is the Earth's solid portion. This includes all of the sediments that form the crust as well as the various layers of the Earth's interior.
Biosphere – This is the sphere in which all living things are a part of. The biosphere contains all of the plants, animals, and other living creatures that exist in our world. This is the sphere that distinguishes our planet from other planets.
Cryosphere – This is the system of the earth that includes all of the frozen, or solid, water of the earth. This includes all snow, ice, glaciers, icebergs, and the arctic climate. The Cryosphere is sort of like a sub sphere of the hydrosphere. This sphere places an important roll in our global climate. It is also a key indicator of climate changes such as global warming.
Anthrosphere – The anthrosphere is the system of humanity. This includes all of the places and things we have built and constructed such as the roadways and buildings in our cities or the farm fields in our rural towns. Every manmade creation, as well as man himself is a part of the anthrosphere.
The Interconnectivity of the Spheres
As you have probably already deduced, all of the spheres are interconnected. All six spheres can exist in one particular location at any given moment in time. The spheres are also dependent on each other. A change in one sphere will result in a change in another. For example, volcanic activity can transfer water from the lithosphere to the atmosphere. Then the water is transferred into the biosphere when a field of corn soaks it up after a good rain. Then the corn enters the anthrosphere where it is processed for human consumption. After consumption, it will enter the lithosphere again. So hopefully you can see that everything we do on this planet affects something else (even if we can't see it, or the effect isn't noticed for years). You can also imagine that as the anthrosphere grows, the cryosphere and biosphere will shrink.
For people concerned with the environment, it is vitally important that they understand the concepts of the interconnected spheres of the Earth.
Farabee, Michael. The Biosphere and Mass Extinctions. Estrella Mountain Community College. May, 2010. <http://www2.estrellamountain.edu/faculty/farabee/biobk/biobookcycles.html>
National Earth Science Teacher’s Association. Layers of Earth’s Atmosphere. Windows to the Universe. 2010. <http://www.windows2universe.org/earth/Atmosphere/layers.html>
Shakhashiri. Chemicals of the Week: Gasses of the Air. November, 2007. <http://scifun.chem.wisc.edu/chemweek/pdf/airgas.pdf>