Skip to main content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
Ecology: Topic Page
Study of the relationships of organisms to their physical environment and to one another.
Biology: Topic Page
Science of life. Biology includes all the life sciences - for example, anatomy and physiology (the study of the structure of living things), cytology (the study of cells), zoology (the study of animals), botany (the study of plants), ecology (the study of habitats and the interaction of living species), animal behavior, embryology, and taxonomy (classification), and plant breeding.
Meteorology: Topic Page
Scientific observation and study of the atmosphere, so that weather can be accurately forecast.
Plate Tectonics: Topic Page
A geological theory according to which the Earth’s crust is composed of a small number of large plates of solid rock, whose movements in relation to each other are responsible for continental drift.
Seismology: Topic Page
Scientific study of earthquakes and related phenomena, including the propagation of waves and shocks on or within the earth by natural or artificially generated seismic signals.
Atmosphere: Topic Page
Mixture of gases surrounding a planet. Planetary atmospheres are prevented from escaping by the pull of gravity.
Climate: Topic Page
Combination of weather conditions at a particular place over a period of time - usually a minimum of 30 years.
Conservation: Topic Page
In the life sciences, action taken to protect and preserve the natural world, usually from pollution, overexploitation, and other harmful features of human activity.
Continental Drift: Topic Page
Geological theory that the relative positions of the continents on the earth's surface have changed considerably through geologic time.
Ecosystem: Topic Page
In ecology, a unit consisting of living organisms and the environment that they live in.
Endangered Species: Topic Page
Any plant or animal species whose ability to survive and reproduce has been jeopardized by human activities.
Erosion: Topic Page
General term for the processes by which the surface of the earth is constantly being worn away.
Evolution: Topic Page
Slow gradual process of change from one form to another, as in the evolution of the universe from its formation to its present state, or in the evolution of life on Earth.
Extinction: Topic Page
In biology, the complete disappearance of a species from the planet.
Global Warming: Topic Page
Increase in average global temperature, amounting to approximately 0.74°C/1.3°F from 1906 to 2005.
Greenhouse Effect: Topic Page
Phenomenon of the Earth's atmosphere by which solar radiation, trapped by the Earth and re-emitted from the surface as long-wave infrared radiation, is prevented from escaping by various gases (the ‘greenhouse gases’) in the air.
Land Use: Topic Page
Exploitation of land for agricultural, industrial, residential, recreational, or other purposes.
Nitrogen Cycle: Topic Page
The continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and denitrification.
Ozone Layer: Topic Page
Or ozonosphere, region of the stratosphere containing relatively high concentrations of ozone, located at altitudes of 12–30 mi (19–48 km) above the earth's surface.
Pollution: Topic Page
Contamination of the environment as a result of human activities.
Recycling: Topic Page
The process of recovering and reusing waste products—from household use, manufacturing, agriculture, and business—and thereby reducing their burden on the environment.
Smog: Topic Page
Smog (smŏg) [smoke+fog], dense, visible air pollution. Smog is commonly of two types.
Vortex Motion: Topic Page
Mass of fluid in whirling or rotary motion.
Weather: Topic Page
State of the atmosphere at a given time and place with regard to temperature, air pressure (see barometer), wind, humidity, cloudiness, and precipitation.
24/7 Reference Desk
, Aeronautical Studies
, Community, Family, and Child Studies
, Computer Technology
, Cosmotology and Esthetics
, Costume & Fashion
, Environmental Studies
, Film, Media and Visual Arts
, Foreign Languages
, Health Sciences
, Hospitality, Tourism & Culinary Arts
, Political Science
, Practice Tests & Career Info
, Religion and Philosophy
, Theater Arts
, Veterinary Tech
, Women's Studies