Jerry Hicks

System - A regularly interacting or interdependant group of items forming a unified whole.

Biosphere - The part of the world in which life can exist.

Hypothesis - A tentative assumption made in order to draw out and test its logical or empirical

consequences.

Geosphere - The solid part of the earth.

Cryposphere - The portion of the earth which consists of the ice masses and snow deposits

which include continental ice sheets, mountainous glaciers, sea ice, surface snow cover

and lake/river ice.

Atmosphere - The gaseous envelope of a celestial body.

Carbon Cycle - The cycle of carbon in the earth's ecosystems in which carbon dioxide is fixed

by photosynthetic organisms to form organic nutrients and is ultimately restored to the inorganic

state by respiration and protoplasmic decay.

Water cycle - The sequence of conditions through which water passes from vapor in the

atmosphere through precipitation upon land or water surfaces and ultimately back into the

atmosphere as a result of evaporation and transpiration.

Ozone (or ozone cycle) - A triatomic very reactive form of oxygen that is a bluish irritating

gas of pungent odor, that is formed naturally in the atmosphere by a photochemical reaction

and is a major air pollutant in the lower atmosphere but a beneficial component of the upper

atmosphere, and that is used for oxidizing, bleaching, disinfecting, and deodorizing.

Radiation balance -

Albedo - The fraction of incident radiation that is reflected by a surface or body.

Greenhouse effect - Warming of surface and lower atmosphere of a planet that is caused by

conversation of solar radiation into heat in a process involving selective transmission of

short wave solar radiation by the atmosphere, its absorption by the planet's surface, and

reradiation as infrared which is absorbed and partly reradiated back to the surface by

atmospheric gases.

Feedback - The return to the input of a part of the output of a machine, system, or process.

Example of Positive feedback:

People make babies, which leads to more people. If the average couple has enough babies for

more than two to survive and reproduce, then the babies lead to more people, which lead to still

more babies, which lead to more people and so on in an accelerating way involving exponential

growth. (http://ftp.shsu.edu/wcb/schools/SHSU/chm/tchastee/13/forums/forum7/messages/47.html)

Example of Negative feedback:

A home thermostat: If its too warm it turns the heat off; it it's too cool it turns the heat

on. This keeps the room temperature stable. (www.ee.nmt.edu/~thomas/ee321_f98/op-amp-ex-neg.html)