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Glossary Search Results
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- Gazetteer
- A list of geographical place or feature names in alphabetical order, usually accompanied by geographic or grid coordinates and basic information about the feature, such as population or classification.
- General Circulation Models (GCMs)
- Large and complex computer programmes that attempt to mathematically simulate global climate. They are based on mathematical equations that seek to represent the physical processes that govern the earth-atmosphere system. (See “Climate Models”). (Source: International Petroleum Industry Environmental Conservation Association (IPIECA), Climate Change A Glossary of terms, 3rd Edition, January 2001. London, 2001.)
- Generalization
- (1) The simplification of shape by the omission of non-essential information,
(2) the combining of small shapes and
(3) the enlargement of certain features essential to the map.
- Geodesy
- The science which describes the size and shape of the Earth in mathematical terms by such direct measurements as triangulation, leveling and gravimetric observations. The aim of geodesy is to support the establishment of a coordinate system used to locate points on the Earth's surface.
- Geographic Information System (GIS)
- A computer-based information system designed to handle georeferenced data which has also the capability to efficiently capture, store, update, manipulate, analyze, display and output a full range of geographical data. Output can be in many forms: either as tables, graphics, or maps.
- Geographic centre
- The point at which a geographical region could be balanced if it were an area of uniform thickness and density.
- Geography
- The science which involves a combination of physical and cultural disciplines which are used to describe, explain and help us to understand our environment and our relationship to it.
- Geoid
- The figure of the Earth considered as a mean sea-level surface extended continuously under the continents.
- Geomatics
- Refers to the disciplines that acquire, store, manage, retrieve, manipulate and distribute spatial or geographically referenced data.
- Geomatics Canada
- Formerly called The Surveys, Mapping and Remote Sensing Sector (part of the Earth Sciences Sector, Natural Resources Canada), this agency is responsible for delivering the federal government's geomatics activities and fostering growth in the Canadian geomatics industry.
- Georeference
- The process of establishing a relationship between data in Cartesian coordinates on a flat map to known ground-truth geographic coordinates. (See Cartesian coordinate system).
- Gestational Age
- Normally identified as the period between the conception and the birth of a baby. The average or normal gestational age of a mature fetus at birth is around 40 weeks. Gestational age categories include: preterm - less than 37 weeks; term - 37 to 42 weeks; post term - greater than 42 weeks.
- Gestational Weight
- The weight of a baby at its specific gestational age. Small for gestational age refers to a weight that is lower than the 10th percentile of the weights observed for babies at a specific gestational age; large for gestational age refers to a weight that is higher than the 90th percentile.
- Glacier
- A huge mass of ice, formed on land by the compaction and re-crystallization of snow, that moves very slowly down slope or outward due to its own weight.
- Global Positioning System (GPS)
- A surveying method that uses a set of 24 satellites in geostationary position high above the Earth. Specially designed GPS receivers, when positioned at a point on Earth, can measure the distance from that point to three or more orbiting satellites. The coordinates of the point are determined through the geometric calculations of triangulation. GPS provides accurate geodetic data for any point on the Earth.
- Global Warming Potential (GWP)
- A time dependent index used to compare the radiative forcing, on a mass basis, of an impulse of a specific greenhouse gas relative to that of CO2. Gases included in the Kyoto Protocol are weighted in the first commitment period according to their GWP over a 100-year time horizon as published in the 1995 Second Assessment Report of the IPCC [Intergovernmental Panel on Climate Change]. In that report, a kilogram of methane, for example has a radiative force of about 21 times greater than that of a kilogram of CO2.The GWP of CO2 is defined as 1, thus methane has a GWP of 21 over the 100-year time horizon. (Source: International Petroleum Industry Environmental Conservation Association (IPIECA), Climate Change A Glossary of terms, 3rd Edition, January 2001. London, 2001).
- Global warming
- Global warming and global cooling refer to the natural warming and cooling trends that the Earth has experienced all through its history. However, the term “global warming” has become popularized as the term that encompasses all aspects of the global warming problem, including the potential climate changes that could be brought about by an increase in greenhouse gases. (Source: Government of Canada Climate Change Site, Glossary of Climate Change Terms)
- Globe
- A scaled down spherical representation or model of the Earth. A map on a sphere.
- Glossary
- An alphabetical list of technical terms and their explanations. A dictionary of technical terms.
- Gnomonic map projection
- A planar map projection which is tangent to the globe at a single point, but may be oriented at any aspect. The projection views the Earth's surface from the centre of the globe. In the polar case, parallels are represented by a system of concentric circles sharing a common point of origin from which radiate the meridians, spaced at true angles. This map projection is primarily used for navigational purposes, as all great circles are represented as straight lines. It may be the oldest map projection, possibly being used by Thales for charts of the heavens, circa 640-548 B.C.
- Gore
- A cresent-shaped map of a region of the Earth between two lines of longitude, which may be fitted to the surface of a globe with a minimum of distortion.
- Government Transfer Payments
- Refers to total income from all transfer payments received from federal, provincial or municipal governments during calendar year 1995. This variable is derived by summing the amounts reported in: the Old Age Security pension and Guaranteed Income Supplement; benefits from Canada or Quebec Pension Plan; benefits from Unemployment Insurance; federal Child Tax benefits; other income from government sources. (Source: 1996 Census Dictionary, Cat. No. 92-351-XPE, Statistics Canada)
- Gradient
- An expression of slope or an angle of slope. Gradient may be expressed as a fraction or percentage, for example, 1/50 (1 in 50) metres indicates that the elevation changes (rises or falls) by one metre in a horizontal distance of 50 metres (or a 2% grade).
- Graphical user interface (GUI)
- A method of interacting with a computer system by using a mouse to point-and-click on graphic symbols (icons, glyphs or menus) which are displayed on the computer monitor. The GUI method allows the user to access software applications and tools with a minimum of keyboarding.
- Graticule
- A network of longitude and latitude lines on a map or chart, providing the basis for a geographical coordinate system with the capability of relating points on a map to their true locations on the Earth.
- Gravure
- A method of printing in which the image is etched into the surface of the printing plate and is therefore, recessed below the surface of the plate. Ink is captured in the recesses of the image and is transferred to paper under firm pressure. (Also called photogravure).
- Great circle
- A circle on the surface of a sphere produced by any plane which passes through the centre of the sphere and intersects the sphere's surface. (Also called an orthodrome).
- Great circle route
- The shortest distance between any two points on a nearly spherical surface like the Earth, is along the arc of a great circle connecting the two points.
- Greenhouse effect
- A process by which the temperature of the Earth is moderated. The Earth’s atmosphere is comprised of a number of gases, some of which have been named “greenhouse gases” because they trap the Sun’s heat near the Earth’s surface and thereby increase the Earth’s temperature. Without the greenhouse effect, the Earth’s average temperature would be –18°C instead of the current 15°C. If it were not for the greenhouse effect, the Earth would be too cold to support life as we know it. (Source: Government of Canada Climate Change Site, Glossary of Climate Change Terms)
- Greenhouse gases (GHGs)
- Gases that accumulate in the Earth’s atmosphere and trap heat. Some occur naturally, such as water vapour, ozone, carbon dioxide, methane, nitrous oxide and other trace compounds, while others are human-made. There are six GHGs covered under the Kyoto Protocol — carbon dioxide (CO2), methane (CH4) and nitrous oxide (N20), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6). (Source: Government of Canada Climate Change Site, Glossary of Climate Change Terms)
- Greenwich Meridian
- The meridian, or line of longitude adopted by international agreement (in 1884) to be the 0° meridian from which all longitudes worldwide would be calculated. (Also called the prime or international meridian).
- Grey Ice
- Young ice 10 – 15 cm thick
- Grey-white Ice
- Young ice 15 – 30 cm thick
- Grid
- A network of regularly spaced straight lines intersecting at right angles and used as a basis for rectangular coordinate map reference systems.
- Grid reference system
- A locational reference system consisting of a grid and a method of referring to points on the grid so that locations can be provided coordinates.
- Gross Rent
- Refers to the total average monthly payments paid by tenant households to secure shelter. Gross rent includes payments for electricity, oil, gas, coal, wood or other fuels, water and other municipal services and monthly cash rent. (Source: Statistics Canada)
- Gross domestic product (GDP)
- The total value of goods and services produced by the nation’s economy before deduction of depreciation charges and other allowances for capital consumption, labour and property located in Canada. It includes the total output of goods and services by private consumers and government, gross private domestic capital investment, and net foreign trade. GDP figures are reported in real 1986 dollars. (Source: Natural Resources Canada, Office of Energy Efficiency, Energy Use Glossary)
- Ground truth data
- The coordinates of a location calculated by accurate measurement on the Earth's surface, as opposed to locational coordinates determined by some other less accurate method, for example, based on a representation of the Earth such as a map.
- Groundwater
- The supply of fresh water found beneath the earth's surface (usually in aquifers) that is often used for supplying wells and springs.
- Groundwater recharge
- The inflow to an aquifer.
- Growing season
- Solid or liquid particles in the size range of 0.001 to 10 microns in radius suspended in the air. Aerosol particles play an important role in the climate system because of their direct interaction (absorption and scattering) with solar and terrestrial radiation, as well as through their influence on cloud formation. (Source: Environment Canada, A Primer on Climate Change, Glossary)
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