Jet streams are fast flowing, relatively narrow air currents found in the atmosphere at around 12 km above the surface of the Earth, just under the tropopause. They form at the boundaries of adjacent ... > more
Hydroelectricity is electricity obtained from hydropower. Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator. Less common variations make ... > more
The greenhouse effect is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface. The name comes from an analogy with the warming of air inside a greenhouse ... > more
The Antarctic ice sheet is the largest single mass of ice on Earth. It covers an area of almost 14 million square km and contains 30 million cubic km of ice. Around 90 percent of the fresh water on ... > more
Kilimanjaro is a mountain in northeastern Tanzania. Kilimanjaro is the tallest free-standing mountain rise in the world, rising 4600 meters (15,000 ft) from the base, and includes the highest peak in ... > more
Homeostasis is the property of an open system, especially living organisms, to regulate its internal environment to maintain a stable, constant condition, by means of multiple dynamic equilibrium ... > more
Global warming refers to the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation.
The global average air temperature ... > more
Sequence stratigraphy is a relatively new branch of geology that attempts to link prehistoric sea-level changes to sedimentary deposits.
The 'sequence' part of the name refers to cyclic sedimentary ... > more
Old growth forest, sometimes called late seral forest or ancient forest or primary forest is an area of forest that has attained great age and exhibits unique biological features. Old growth forests ... > more
The Great Lakes are a group of five large lakes on or near the United States-Canadian border. They are the largest group of fresh water lakes on the earth and the Great Lakes-St. Lawrence system is ... > more