LATITUDE AND LONGITUDE
To pinpoint y The co-ordinate system adopted for the earth is related directly to its axis of rotationwhich, for practical purposes, is deemed to be fixed and defines the north-south direction in space. The axis cuts the earths surface at the North and South Poles. The plane of the equator which cuts the earth's surface at the equator. all points on the equator are thus equidistant from the poles,
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our position on a map of the world you need to work out your coordinates, known as latitude and longitude.
Latitude is your position North or South of the equator, lines or parallels are drawn around the Earth at intervals. The North pole is assigned the latitude 90 deg N and the South pole 90 deg S. |
The equator is given a latitude value of zero degrees and therefore the latitude of any point on the earths surface is the angle at the centre of the earth measured north or south of, and perpendicular to, the equator
The Greenwich meridian is generally accepted as the prime meridian but others are in use , eg Paris and Rome. |
The great semi circles joining the poles are described as meridans, one of which is arbitrarily selected as prome meridan with an assigned value of zero degrees. Then the longitude of any point on the earths surface is the angle at the centre of the earth measured east or west in the plane of the equator, between the palne of the prime meridian and the plane of the meridian passing through the point..
Longitude lines run along the Earths surface in a North - South directions, and unlike latitude lines, they divide the globe into segments like those of a orange.
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Longitude Lines of longitude, or meridans, are drawn a little differently. The line of longitude corresponding to 0 degrees which passes through Greenwich in London, is called the prime meridan.Longitude is measured in degrees East or West of the prime merdian. This means one half of the world is measured in degrees of east longitude up to 180 degrees, and the other half in degrees of west longitude up to 180 degrees. Latitude is measured from 0 degrees to 90 degrees north or south of the equator. For greater precision, degrees of latitude and longitude are divided into 60 minutes and minutes are divided into 60 seconds. Maps are often marked with parallels and meridians. The latitude and longitude of a point are called its coordinates. If you know the coordinates, you can use a map to locate any point on the Earth. Degrees, Minutes and Seconds DDD MM SS.S 31 18' 20.2N 120 34' 49.3W This is the most common format used in marking your position on a map. Its also the most cumbersome to work with. Its like telling the time, unlike the grid system which is easier and quicker. Degrees and Decimal Minutes DDD MM.MMM 30 15.371'N 120 33.871'W This is the format most commonly use when working with electronic navigation equipment. |
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Latitude and Longitude Coordinates UK The latitude and longitude coordinates that cover most of mainland UK are as follows: Latitude from 50 North to 60 North and Longitude from 8 West to 2 East. |
Note: If you look at the two examples above you will see that the position of Salisbury Cathedrals Spire is at 51 deg 03' .51N 001 deg 47' .45W |
The Latitude and
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Longitude coordinates are found at the extreme edge of Ordnance Survey maps indicated by a bold black line with the latitude coordinates left and right hand sides and longitude bottom and top of the map. Graticle intersecti
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on, these are the small blue crosses that you see on the map they are spaced at 5' intervals over the map, they are used when taking latitude and longitude coordinates to and from the map.
