Glossary

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Term Term description
gamma rays

A stream of electromagnetic radiation having wavelengths shorter than those of x-rays and therefore greater energy and penetrating power. Gamma rays are given off by unstable nuclei during radioactive decay.

generosity

The moral virtue of selfless giving and sharing.

geologic uplift

Vertical elevation of the Earth’s surface, usually in response to moving tectonic plates.

geological timescales

The geological time scale (GTS) relates the position of buried rock layers to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships between events that have occurred throughout Earth’s history. A basic principle of GTS is the idea that the deeper a layer is, the further in the past it was deposited.

geyser

A natural hot spring that intermittently ejects a column of water and steam into the air.

glacial cycles

Periods of time when large glacial ice sheets cover parts of the Earth's surface. The most recent glacial period occurred between about 12,000 and 11,500 years ago in Northern Europe and North America.

glaciations

The condition of being covered with glaciers or masses of ice.

glacier

A large mass of ice moving very slowly through a valley or spreading outward from a center. Glaciers form over many years from packed snow in areas where snow accumulates faster than it melts. A glacier is always moving, but when its forward edge melts faster than the ice behind it advances, the glacier as a whole shrinks backward.

global climate change

Any significant change in the measures of climate that occur over several decades or longer; most notable today is the ongoing rise in global average temperature near Earth's surface, caused mostly by increased concentrations of greenhouse gases in the atmosphere.

global warming

Global warming is the term used to describe an increase in the average temperature of the Earth's atmosphere and its oceans, a change that is believed to be permanently altering the Earth’s climate. The scientific consensus on climatic change related to global warming is that the average temperature of the Earth has risen between 0.4 and 0.8 °C over the past 100 years. The increased volumes of carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land clearing, agriculture, and other human activities, are the primary causes of the global warming that has occurred over the past 50 years.

glucose

A simple sugar that is an important energy source in living organisms and is a component of many carbohydrates. A hexose; chemical formula: C6H12O6.

God

The perfect and all-powerful spirit or being that is worshipped especially by Christians, Jews, and Muslims as the one who created and rules the universe.

grace

In Christian belief, the blessing of God as manifested in human life and in all of God's creation.

gratitude

The quality of being thankful; readiness to show appreciation for and to return kindness.

gravitational attractions

The force of attraction between all masses in the universe; gravitational attraction keeps objects grounded on the Earth's surface, moons orbiting planets, planets orbiting the sun, and the sun in its arm of the Milky Way Galaxy.

gravitational energy

The energy an object possesses because of its position in a gravitational field.

gravity

The force that attracts a body toward the center of the earth, or toward any other physical body having mass. The force that attracts any two masses along a line that connects their centers.

greenhouse effect

A phenomenon in which the atmosphere of a planet traps radiation emitted by its sun, caused by gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but retain heat radiated back from the planet's surface.

greenhouse gas

A gas in the atmosphere that absorbs and emits radiation within the thermal infrared range. This property allows the earth to maintain it's warm temperature which supports life on earth. Water vapor, carbon dioxide, ozone, and methane are good examples of gases with this property. When the concentration of these gases gets too high, the earth warms beyond its normal range and many catastrophic climate shifts occur.

greenhouse gas

a gas in the atmosphere that absorbs and emits radiation within the thermal infrared range

greenhouse gases

A gas in the atmosphere that absorbs and emits radiation within the thermal infrared range. This property allows the earth to maintain its warm temperature which supports life on earth. Water vapor, carbon dioxide, ozone, and methane are good examples of gases with this property. When the concentration of these gases gets too high, the earth warms beyond its normal range and many catastrophic climate shifts occur.

gross domestic product

The total market value of all the goods and services produced within the borders of a nation during a specified period. GDP is used as an indicator of the economic health of a country, however, many people agree it is not a good indicator of well-being since GDP includes the cost of negative influences on well-being such as war, environmental toxic spill clean-ups, and natural disaster.

ground source heat pumps

Central heating and/or cooling system that transfers heat to or from the ground. It uses the earth as a heat source (in the winter) or a heat sink (in the summer).

groundwater

Water that collects or flows beneath the Earth's surface, filling the porous spaces in soil, sediment, and rocks. Groundwater originates from rain and from melting snow and ice and is the source of water for aquifers, springs, and wells. The upper surface of groundwater is the water table.

gypsum

(CaSO4) A very common, widely mined, soft mineral consisting of hydrous calcium sulfate that can be used as a fertilizer, in making plaster of Paris and chalk.

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