"Spheres" of the Earth

The Earth is a complex system that can be thought of as consisting of a number of interacting "spheres". Many of these spheres are abiotic (non-living)

1. Lithosphere- The lithosphere is the outer solid part of the earth, including the crust and uppermost mantle. The lithosphere is about 100 km thick, although its thickness is age dependent (older lithosphere is thicker).

2. Atmosphere- The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night. Dry air contains roughly (by volume) 78% nitrogen, 21% oxygen, 0.93% argon, 0.038% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1%.

3. Hydrosphere- The hydrosphere is often called the "water sphere" as it includes all the earth's water found in streams, lakes, the soil, groundwater, and in the air. The hydrosphere interacts with, and is influenced by, all the other earth spheres. The water of the hydrosphere is distributed among several different stores found in the other spheres. Water is held in oceans, lakes and streams at the surface of the earth. Water is found in vapor, liquid and solid states in the atmosphere. The biosphere serves as an interface between the spheres enabling water to move between the hydrosphere, lithosphere and atmosphere as is accomplished by plant transpiration. The hydrologic cycle traces the movement of water and energy between these various stores and spheres.

4. Crysosphere- The cryosphere is the part of the earth's hydrosphere comprised of frozen water. It plays a integral role in the global climate system through its influence on surface energy budgets, atmospheric moisture, hydrology, and atmospheric and oceanic circulation. The cyrosphere is a sensitve element of the climate system providing a key indicator of climate change. The increasing loss of Arctic sea ice and breakup of Antarctic ice shelves are are two examples.

Other of these spheres containg the biotic (living) components of the earth.

1. Biospshere- The biosphere is the biological component of earth systems, which also include the lithosphere, hydrosphere, atmosphere and other "spheres" (e.g. cryosphere, anthrosphere, etc.). The biosphere includes all living organisms on earth, together with the dead organic matter produced by them.

2. Anthrosphere- The anthrosphere.is that part of the environment that is made or modified byhumans for use in human activities.

Readings

Biosphere- http://www.eoearth.org/article/Biosphere

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

1. define the lithosphere, atmosphere, hydrosphere, crysosphere, biosphere, and anthrosphere

2. discuss how humans depend on each of the abiotic spheres

3. discuss how humans can be affected by the different abiotic spheres

4. disucs how humans affect the different abiotic spheres