DEFINITIONS: The biosphere is a closed self-regulating system that integrates living organisms with nonliving components of a planet (Lenkeit). The biosphere is part of the outer shell of a planet and includes the atmosphere, hydrosphere, and lithosphere (answers. com). The hydrosphere is an open system that contains all of a planet's solid, liquid, and gaseous water (Answers. com). As an open system, the hydrosphere interacts with the surrounding systems through inputs and outputs (Lenkeit).

The atmosphere is an open system that consists of a gaseous mixture enveloping a planet (Answers. com). These gasses, known as air, include O 2, N 2 and H 2 O. The atmosphere is also composed of water, ice and dust particles. Atmosphere functions like a blanket, keeping Earth's heat from escaping into space (Lenkeit). It has also been compared to a greenhouse: like glass it lets short wave insulation inside, but keeps most of long wave ground radiation from going out (Lenkeit).

The lithosphere is an open system, which contains all of the cold, hard, solid rock of the planet's crust (surface), the hot semi-solid rock that lies underneath the crust, the hot liquid rock near the center of the planet, and the solid iron core (center) of the planet (Answers. com). On Earth, the lithosphere comprises the crust and the upper part of the mantle. The lithosphere is about sixty miles thick (Lenkeit). INTERACTIONS: The four spheres of the Earth system are highly interdependent causing interactions between the spheres to have many cause and effect relationships. A change in one sphere can cause changes in another sphere, which may cause changes in yet another sphere.

The biosphere is sustained through interactions with the gasses from the atmosphere, minerals of the lithosphere, and water of the hydrosphere in the energy cycle (Answers. com). The atmosphere is essential for the biosphere because it supplies oxygen, water, CO 2 and some nutrients (N) to living organisms, and protects living organisms from temperature extremes and excessive UV radiation (Answers. com). Outside of the biosphere, the atmospheric interacting with the lithosphere and hydrosphere is when the ocean waves are affected by the wind being slowed by friction from the land (Lenkeit). The lithosphere interacts with the hydrosphere and atmosphere through processes such as erosion where rock and soil become removed through physical and chemical weathering.

The hydrosphere includes the water in the atmosphere, under and within the lithosphere, the water in plants and animals of the biosphere, and the water covering the surface of the planet. In general, many events in the Earth System can be described using the cause and effect relationship of interactions between the four spheres. WORKS CITED: Answers. com. "Biosphere." Answers.

com. 1 Sept. 2005. Lenkeit, K. A. "Physical Geography." Foothill-De Anza Community College District & The William and Flora Hewlett Foundation.

2004. 1 Sept. 2005.