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Ordnance Survey National Grid
The ORDNANCE SURVEY NATIONAL GRID REFERENCE SYSTEM is a system of geographic grid references used in Great Britain, different from using Latitude
Latitude
and Longitude
Longitude
. It is often called BRITISH NATIONAL GRID (BNG). The Ordnance Survey
Ordnance Survey
(OS) devised the national grid reference system, and it is heavily used in their survey data, and in maps based on those surveys, whether published by the Ordnance Survey
Ordnance Survey
or commercial map producers. Grid references are also commonly quoted in other publications and data sources, such as guide books or government planning documents. A number of different systems exist that can provide grid references for locations within the British Isles
British Isles
: this article describes the system created solely for Great Britain and its outlying islands (including the Isle of Man
Isle of Man
); the Irish grid reference system
Irish grid reference system
is a similar system created by the Ordnance Survey
Ordnance Survey
of Ireland for the island of Ireland
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National Grid (Great Britain)
The NATIONAL GRID is the high-voltage electric power transmission network in Great Britain, connecting power stations and major substations and ensuring that electricity generated anywhere in England, Scotland and Wales can be used to satisfy demand elsewhere. The UK grid is connected as a wide area synchronous grid nominally running at 50 hertz. There are also undersea interconnections to northern France ( HVDC Cross-Channel
HVDC Cross-Channel
), Northern Ireland ( HVDC Moyle ), the Isle of Man ( Isle of Man to England Interconnector ), the Netherlands ( BritNed ) and the Republic of Ireland ( EirGrid
EirGrid
). On the breakup of the Central Electricity Generating Board in 1990, the ownership and operation of the National Grid in England and Wales passed to National Grid Company plc, later to become National Grid Transco, and now National Grid plc
National Grid plc
. In Scotland the grid split into two separate entities, one for southern and central Scotland and the other for northern Scotland, connected by interconnectors to each other. The first is owned and maintained by SP Energy Networks, a subsidiary of Scottish Power , and the other by SSE . However, National Grid plc
National Grid plc
remains the System Operator for the whole UK Grid
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Geodesy
GEODESY ( /dʒiːˈɒdᵻsi/ ), — also known as GEODETICS, GEODETIC ENGINEERING or GEODETICS ENGINEERING — a branch of applied mathematics and earth sciences , is the scientific discipline that deals with the measurement and representation of the Earth (or any planet ), including its gravitational field , in a three-dimensional time-varying space. Geodesists also study geodynamical phenomena such as crustal motion, tides , and polar motion . For this they design global and national control networks , using space and terrestrial techniques while relying on datums and coordinate systems
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Geodynamics
GEODYNAMICS is a subfield of geophysics dealing with dynamics of the Earth . It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading , mountain building , volcanoes , earthquakes , faulting and so on. It also attempts to probe the internal activity by measuring magnetic fields , gravity, and seismic waves , as well as the mineralogy of rocks and their isotopic composition . Methods of geodynamics are also applied to exploration of other planets. CONTENTS * 1 Overview * 2 Deformation of rocks * 2.1 Elastic * 2.2 Ductile * 2.3 Brittle * 2.4 Deformation structures * 3 Thermodynamics * 4 Dynamics of the Earth * 5 Methods * 6 See also * 7 References * 8 External links OVERVIEW Geodynamics is generally concerned with processes that move materials throughout the Earth. In the Earth’s interior , movement happens when rocks melt or deform and flow in response to a stress field . This deformation may be brittle , elastic , or plastic , depending on the magnitude of the stress and the material’s physical properties, especially the stress relaxation time scale. Rocks are structurally and compositionally heterogeneous and are subjected to variable stresses, so it is common to see different types of deformation in close spatial and temporal proximity
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Geomatics
GEOMATICS (including GEOMATICS ENGINEERING), also known as SURVEYING ENGINEERING or GEOSPATIAL SCIENCE (including GEOSPATIAL ENGINEERING and GEOSPATIAL TECHNOLOGY), is the discipline of gathering, storing, processing, and delivering geographic information or spatially referenced information. In other words, it "consists of products, services and tools involved in the collection, integration and management of geographic data". CONTENTS * 1 Overview and etymology * 2 Science * 3 Engineering * 4 Applications * 5 Areas of knowledge * 6 See also * 7 References * 8 Further reading * 9 External links OVERVIEW AND ETYMOLOGYMichel Paradis, a French-Canadian surveyor, introduced _geomatics_ as a new scientific term in an article published in 1981 in _The Canadian Surveyor_ and in a keynote address at the centennial congress of the Canadian Institute of Surveying in April 1982. He claimed that at the end of the 20th century the needs for geographical information would reach a scope without precedent in history and in order to address these needs, it was necessary to integrate in a new discipline both the traditional disciplines of land surveying and the new tools and techniques of data capture, manipulation, storage and diffusion
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Cartography
CARTOGRAPHY (from Greek χάρτης _khartēs_, "papyrus, sheet of paper, map"; and γράφειν _graphein_, "write") is the study and practice of making maps . Combining science , aesthetics , and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively. The fundamental problems of traditional cartography are to: * Set the map's agenda and select traits of the object to be mapped. This is the concern of map editing. Traits may be physical, such as roads or land masses, or may be abstract, such as toponyms or political boundaries. * Represent the terrain of the mapped object on flat media. This is the concern of map projections . * Eliminate characteristics of the mapped object that are not relevant to the map's purpose. This is the concern of generalization . * Reduce the complexity of the characteristics that will be mapped. This is also the concern of generalization. * Orchestrate the elements of the map to best convey its message to its audience. This is the concern of map design .Modern cartography constitutes many theoretical and practical foundations of geographic information systems . CONTENTS * 1 History * 2 Technological changes * 3 Deconstruction * 4 Map types * 4.1 General vs. thematic cartography * 4.2 Topographic vs
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History Of Geodesy
Geodesy
Geodesy
(/dʒiːˈɒdɨsi/), also named geodetics, is the scientific discipline that deals with the measurement and representation of the Earth. The HISTORY OF GEODESY began in antiquity and blossomed during the Age of Enlightenment . Early ideas about the figure of the Earth
Earth
held the Earth
Earth
to be flat (see flat Earth
Earth
), and the heavens a physical dome spanning over it. Two early arguments for a spherical Earth
Earth
were that lunar eclipses were seen as circular shadows which could only be caused by a spherical Earth, and that Polaris
Polaris
is seen lower in the sky as one travels South. CONTENTS* 1 Hellenic world * 1.1 Hellenistic world * 2 Ancient India * 3 Islamic world * 3.1 Al-Biruni * 4 Medieval Europe
Europe
* 5 Early modern period * 5.1 Europe
Europe
* 5.2 Asia and Americas * 6 19th century * 7 See also * 8 Notes * 9 References * 10 External links HELLENIC WORLDThe early Greeks , in their speculation and theorizing, ranged from the flat disc advocated by Homer
Homer
to the spherical body postulated by Pythagoras
Pythagoras
. Pythagoras's idea was supported later by Aristotle
Aristotle

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Geographical Distance
GEOGRAPHICAL DISTANCE is the distance measured along the surface of the earth . The formulae in this article calculate distances between points which are defined by geographical coordinates in terms of latitude and longitude . This distance is an element in solving the second (inverse) geodetic problem . CONTENTS* 1 Introduction * 1.1 Nomenclature * 1.2 Singularities and discontinuity of latitude/longitude * 2 Flat-surface formulae * 2.1 Spherical Earth projected to a plane * 2.2 Ellipsoidal Earth projected to a plane * 2.3 Polar coordinate flat- Earth formula * 3 Spherical-surface formulae * 3.1 Tunnel distance * 4 Ellipsoidal-surface formulae * 4.1 Lambert\'s formula for long lines * 4.2 Bowring\'s method for short lines * 5 See also * 6 References * 7 External links INTRODUCTIONCalculating the distance between geographical coordinates is based on some level of abstraction; it does not provide an _exact_ distance, which is unattainable if one attempted to account for every irregularity in the surface of the earth. Common abstractions for the surface between two geographic points are: * Flat surface; * Spherical surface; * Ellipsoidal surface.All abstractions above ignore changes in elevation. Calculation of distances which account for changes in elevation relative to the idealized surface are not discussed in this article
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Geoid
The GEOID is the shape that the surface of the oceans would take under the influence of Earth\'s gravity and rotation alone, in the absence of other influences such as winds and tides. This surface is extended through the continents (such as with very narrow hypothetical canals). All points on a geoid surface have the same gravitational potential energy (the sum of gravitational potential energy and centrifugal potential energy). The geoid can be defined at any value of gravitational potential such as within the Earth 's crust or far out in space, not just at sea level . The force of gravity acts everywhere perpendicular to the geoid, meaning that plumb lines point perpendicular and water levels parallel to the geoid if only gravity and rotational acceleration were at work. Specifically, the geoid is the equipotential surface that would coincide with the mean ocean surface of Earth if the oceans and atmosphere were in equilibrium, at rest relative to the rotating Earth, and extended through the continents (such as with very narrow canals). According to Gauss , who first described it, it is the "mathematical figure of Earth", a smooth but highly irregular surface whose shape results from the uneven distribution of mass within and on the surface of Earth. It does not correspond to the actual surface of Earth's crust, but to a surface which can only be known through extensive gravitational measurements and calculations
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Figure Of The Earth
The expression FIGURE OF THE EARTH has various meanings in geodesy according to the way it is used and the precision with which the Earth 's size and shape is to be defined. While the sphere is a close approximation of the true figure of the Earth and satisfactory for many purposes, geodesists have developed several models that more closely approximate the shape of the Earth so that coordinate systems can serve the precise needs of navigation , surveying , cadastre , land use , and various other concerns. CONTENTS * 1 Need for models of the figure of the Earth * 2 Models of the figure of the Earth * 2.1 Sphere * 2.2 Ellipsoid of revolution * 2.3 More complicated shapes * 2.4 Geoid * 3 Earth rotation and Earth\'s interior * 4 Global and regional gravity field * 5 Volume * 6 See also * 7 Notes and references * 8 External links NEED FOR MODELS OF THE FIGURE OF THE EARTHThe actual topographic surface is most apparent with its variety of land forms and water areas. This is, in fact, the surface on which actual Earth measurements are made. However, it is not feasible for exact mathematical analysis, because the formulas which would be required to take the irregularities into account would necessitate a prohibitive amount of computation. The topographic surface is generally the concern of topographers and hydrographers
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Geodetic Datum
A GEODETIC DATUM or GEODETIC SYSTEM is a coordinate system , and a set of reference points, used to locate places on the Earth (or similar objects). An approximate definition of sea level is the datum WGS 84 , an ellipsoid , whereas a more accurate definition is Earth Gravitational Model 2008 (EGM2008), using at least 2,159 spherical harmonics . Other datums are defined for other areas or at other times; ED50 was defined in 1950 over Europe and differs from WGS 84 by a few hundred meters depending on where in Europe you look. Mars has no oceans and so no sea level, but at least two martian datums have been used to locate places there. Datums are used in geodesy , navigation , and surveying by cartographers and satellite navigation systems to translate positions indicated on maps (paper or digital) to their real position on Earth . Each starts with an ellipsoid (stretched sphere), and then defines latitude , longitude and altitude coordinates. One or more locations on the Earth's surface are chosen as anchor "base-points". The difference in co-ordinates between datums is commonly referred to as _datum shift_. The datum shift between two particular datums can vary from one place to another within one country or region, and can be anything from zero to hundreds of meters (or several kilometers for some remote islands)
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Geodesic
In differential geometry , a GEODESIC (/ˌdʒiːəˈdɛsɪk, ˌdʒiːoʊ-, -ˈdiː-, -zɪk/ ) is a generalization of the notion of a "straight line " to "curved spaces ". The term "geodesic" comes from _geodesy _, the science of measuring the size and shape of Earth ; in the original sense, a geodesic was the shortest route between two points on the Earth's surface , namely, a segment of a great circle . The term has been generalized to include measurements in much more general mathematical spaces; for example, in graph theory , one might consider a geodesic between two vertices /nodes of a graph . In the presence of an affine connection , a geodesic is defined to be a curve whose tangent vectors remain parallel if they are transported along it. If this connection is the Levi-Civita connection induced by a Riemannian metric , then the geodesics are (locally ) the shortest path between points in the space. Geodesics are of particular importance in general relativity . Timelike geodesics in general relativity describe the motion of free falling test particles
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Geographic Coordinate System
A GEOGRAPHIC COORDINATE SYSTEM is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents a vertical position , and two or three of the numbers represent a horizontal position . A common choice of coordinates is latitude , longitude and elevation . To specify a location on a two-dimensional map requires a map projection
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Horizontal Position Representation
A POSITION REPRESENTATION is the parameters used to express a position relative to a reference. Representing position in three dimensions is often done by a Euclidean vector . However, when representing position relative to the Earth it is often more convenient to represent vertical position as altitude or depth, and to use some other parameters to represent HORIZONTAL POSITION. There are also several applications where only the horizontal position is of interest, this might e.g. be the case for ships and ground vehicles/cars. There are several options for horizontal position representations, each with different properties which makes them appropriate for different applications. Latitude /longitude and UTM are common horizontal position representations. The horizontal position has two degrees of freedom , and thus two parameters are sufficient to uniquely describe such a position. However, similarly to the use of Euler angles as a formalism for representing rotations , using only the minimum number of parameters gives singularities , and thus three parameters are required for the horizontal position to avoid this
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Latitude
In geography , LATITUDE is a geographic coordinate that specifies the north –south position of a point on the Earth's surface. Latitude
Latitude
is an angle (defined below) which ranges from 0° at the Equator
Equator
to 90° ( North
North
or South) at the poles. Lines of constant latitude, or _parallels_, run east–west as circles parallel to the equator. Latitude
Latitude
is used together with longitude to specify the precise location of features on the surface of the Earth. Without qualification the term latitude should be taken to be the _geodetic latitude_ as defined in the following sections. Also defined are six _auxiliary latitudes_ which are used in special applications
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Longitude
LONGITUDE (/ˈlɒndʒᵻtjuːd/ or /ˈlɒndʒᵻtuːd/ , Australian and British also /ˈlɒŋɡᵻtjuːd/ ), is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians (lines running from the North Pole
North Pole
to the South Pole
South Pole
) connect points with the same longitude. By convention, one of these, the Prime Meridian
Prime Meridian
, which passes through the Royal Observatory, Greenwich , England, was allocated the position of zero degrees longitude. The longitude of other places is measured as the angle east or west from the Prime Meridian, ranging from 0° at the Prime Meridian
Prime Meridian
to +180° eastward and −180° westward. Specifically, it is the angle between a plane containing the Prime Meridian
Prime Meridian
and a plane containing the North Pole, South Pole
South Pole
and the location in question
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