Geographic coordinate system
Geographic coordinate system is a prevalent spherical coordinate recommendation system for specifying location of attributes on the curved surconfront of the earth. A netjob-related of intersecting lines consisting of north-south lines of longitude and east-west lines of latitude creates an imaginary mesh approximately the world. Such a network-related (graticule) enables for the description of the position of any suggest on the surchallenge of the earth.
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Geographic coordinates of a point is a set of two numbers, namely latitude and also longitude (regularly abbreviated as lat long) that specify the location of that point. The two coordinates are angular dimensions. Latitude gives an angular meacertain of the distance of the suggest north or south of the equator, while longitude refers to the east-west angular meacertain family member to the prime meridian.
Latitude – Line of Latitude
Latitude (geodetic latitude) of a allude is the angle (φ) in between the plane of the equator and a line passing through the allude perpendicular to the surface of the ellipsoidal earth. The line drawn from the suggest on earth's surface does not pass with the center of the earth except for points on the poles and also the equator. When referring to latitude commonly the geodetic latitude is meant.
Geocentric latitude of a allude on the surconfront of the earth is the angle between the airplane of the equator and the line connecting the suggest to the facility of the spherical earth.
Latitude deserve to be assumed of as the angular distance of a suggest (on the surconfront of earth) north or southern of the equator. Since the plane of equator is the reference plane for measuring latitudes, equator is at 0° latitude. Equatorial aircraft divides the earth into 2 equal hemispheres. Latitudes are designated via N (north) for locations north of the equator and via S (south) for places south of the equator. Latitude angles may additionally be assigned positive values for northern hemisphere and negative values for southern hemispbelow. North Pole is at 90°N, and South Pole's latitude is 90°S or -90°.
A line (arc) on the world or on a map running east-west and connecting all points through the same latitudinal angle is dubbed a line of latitude, parallel or a circle of latitude. Lines of latitude create circles about the earth parallel to the equator and each various other. Equator is a great circle via a circumference equal to the earth's and also focused on the facility of the earth. Parallels run equally spaced from 0° at the equator to 90° at the poles with successively smaller diameters approaching the poles. Other than the equator, parallels have actually a smaller circumference than the earth, and their center does not coincide through that of the earth, and also hence they are tiny circles. Parallels at the North and South poles are effectively points quite than circles. The distances in between each level of latitude are even more or less constant and are close to 111 kilometres, 69 statute miles or 60 nautical miles.
Keep in mind that latitude is the angle; thus a allude at 35° north latitude refers to the angle of 35° between the plane of equator and the line connecting this suggest to the center of earth. Parallel or line of latitude is the line; the line connecting all points at 35° latitude is dubbed the 3fifth parallel. Both describe the distance in degrees north of the equator.
Latitude and Geographic Zones
The levels of latitude north or south of the equator and also the seaboy of the year influence the amount of solar power obtained in various areas of the earth. As an outcome, different geographical zones can be categorized based on their characteristic climate and also setting. Such latitudinal geographical zones encompass equatorial and also tropical, subtropical, midlatitude, subarctic or subantarctic, and arctic or antarctic.
Lines of latitude or parallels of importance include: Tropic of Cancer at 23.5°N parallel, Tropic of Capricorn at 23.5°S parallel, equator at 0°, Arctic Circle at 66.5°N parallel, and also Antarctic Circle at 66.5°S parallel.
Longitude – Line of Longitude
The longitude of a allude on the surchallenge of the earth is the angular distance (λ) eastern or west from a reference line dubbed prime meridian that runs from North Pole to South Pole. Being a reference line or origin for measuring angles, the prime meridian has a longitude of 0°.
Historically tright here have actually been a number of referral lines for measuring longitude. The present prime meridian was characterized by an global agreement in 1884 to be an imaginary line connecting North Pole to South Pole and passing via Greenwich, England also. Prime Meridian is additionally referred to as Greenwich Meridian.
A line (arc) on the world or on a map running north-south connecting North Pole to South Pole and through all points via the exact same longitudinal angle is dubbed a line of longitude or a meridian. Each meridian forms fifty percent of a good circle, assuming a spherical earth. Meridians intersect lines of latitude (parallels) at ideal angles. The spherical earth is separated into 360 levels east-west. Lines of longitude variety from 0° to 180° to the east and also from 0° to -180° to the west of the prime meridian. 180° east or west longitude is the meridian opposite the prime meridian and also synchronizes through the International Date Line (IDL has actually some deviations from the straight meridian line). The aircraft intersecting the earth at prime meridian and also 180° meridian divides the earth into western and also eastern hemispheres. Longitudes are designated through E (east) for locations eastern of the prime meridian and also with W (west) for areas west of the prime meridian. Longitude angles might additionally be assigned positive worths for the eastern hemisphere and also negative values for western hemisphere.
Comparable to latitude, longitude is the angle; a point being at 122° longitude describes the horizontal angle of 122° between the line connecting the point to the facility of the earth and the prime meridian's aircraft. Meridian or line of longitude is the line; thus the line connecting all points at -122° longitude is the 122°W meridian. Both refer to the distance in levels from the prime meridian.
On a spherical recommendation surchallenge of the earth such as a world, lines of longitude are not parallel (as opposed to lines of latitude), fairly they converge towards the poles. The ground distance of a degree of longitude is at its best (about 111km or 69 miles) at the equator and also decreases to 0 at the poles. At 40° latitude, one degree of longitude is around 85.4kilometres, and also at 60° latitude, it spans a distance of roughly 55.8kilometres.
Lines of latitude and also longitude develop an imaginary grid that covers the globe. Such a network of parallels and also meridians is known as the graticule. The combicountry of latitude and also longitude angles comprises the geographic works with of a allude on the surface of the earth, and also enables for the specification of its position. When specifying the works with of a point latitude is written before longitude.
Latitude longitude works with - styles and also conversion
In order to be able to describe the place of a suggest on the surconfront of the earth via acceptable accuracy, smaller sized sections of the angular measurement compared to levels should be supplied. For example, as pointed out a degree of latitude is around 111kilometres, such a distance does not enable for specific pinpointing of the place of a suggest between 3fifth and also 3sixth parallel over the equator. As a result levels of latitude and longitude are better subsplit into smaller sections. Each degree ( ° ) is separated into 60 minutes of arc ( ′ ), and also each minute is divided into 60 secs of arc ( ″ ). 1° = 60′ = 3600″; and also 1′ = 60″. A latitude or longitude coordinate might be composed in among 3 formats.
Degrees Minutes Seconds (DMS) - ddd° mm′ ss.s″:
As the name suggests, in the DMS format latitude and longitude coordinates are delisted via the levels, minutes and also seconds values. Degrees are integer and also selection from 0° to 90° and 0 to -90° for latitude, and also 0° to 180° and also 0 to -180° for longitude; minutes are additionally integer, and secs deserve to be composed as integer or genuine number (decimal). Keep in mind that given that 1° = 60′, if you have actually 60′, you can lug over and add 1° to the degree part instead; and also similarly if you have actually 60″, you deserve to lug over and add 1′ to the minute part rather. Because of this minutes and also seconds have the right to always be created much less than 60. Example: 45° 36′ 23″ N 122° 46′ 18.4″ W; 46° 73′ 43″ N 118° 36′ 83.6″ W can be created as 47° 13′ 43″ N 118° 37′ 23.6″ W (for latitude coordinate 73′ = 1° 13′ and also for longitude coordinate 83.6″ = 1′ 23.6″).
Degrees Decimal Minutes - ddd° mm.mmm′:
Here the levels are integer values while the minutes are composed as genuine number (decimal). The decimal component holds the fractions of the minute; therefore tright here is no secs component. Example: 23° 34.56′ S 109° 23.72′ E
Decimal Degrees - ddd.ddddd°:
In this format latitude and also longitude collaborates are delisted only by levels as real (decimal) number. Any minutes and seconds can be converted to fractions of a degree as decimals. Example: 46.3678° -122.28453° (positive latitude is north, negative longitude is west).
Often times, tbelow is a need for convariation in between various geographic coordinate styles. Converting in between formats is disputed in information below. It is beneficial to remember some prevalent relations in between levels, minutes and also seconds: 60′ = 1°, 30′ = 0.5°, 15′ = 0.25°, and 45′ = 0.75°; similarly 60″ = 1′, 30″ = 0.5′, 15″ = 0.25′, and 45″ = 0.75′.
Convert minutes to degrees: degrees = minutes / 60 Convert levels to minutes: minutes = levels x 60 Convert seconds to degrees: levels = secs / 3600 Convert degrees to seconds: seconds = degrees x 3600 Convert secs to minutes: minutes = secs / 60 Convert minutes to seconds: seconds = minutes x 60
Convert Degrees Minutes Seconds (DMS) to Decimal Degrees
This convariation is accomplished by converting minutes to degrees, as well as converting secs to degrees, and then including the outcomes to the original entirety levels. Decimal Degrees = Degrees + (Minutes / 60) + (Seconds / 3600) Example - transform 38° 12′ 46″ to decimal degrees: 12′ = 0.2° and 46″ = 0.01278° 38° 12′ 46″ = 38° + (12 / 60)° + (46 / 3600)° = 38° + 0.2° + 0.01278° = 38.21278°
Convert Degrees Minutes Seconds to Degrees Decimal Minutes
Seconds must be converted to minutes, and also the result included to the original whole minutes. Degrees Decimal Minutes = Degrees and (Minutes + (Seconds / 60)) Example - convert 38° 12′ 46″ to decimal degrees: 46″ = 0.767′ 38° 12′ 46″ = 38° 12′ + (46 / 60)′ = 38° (12 + 0.767)′ = 38° 12.767′
Convert Decimal Degrees to Degrees Decimal Minutes
In this conversion, the totality number of degrees is known; the decimal part of the degree demands to be converted to minutes. The (-) sign in a decimal levels coordinate denotes south if the coordinate is a latitude or west if it is longitude. Example - transform 68.4673° to levels decimal minutes: The value of whole levels is 68°; by subtracting the totality degree from the original coordinate, the fractional component of levels results (68.4673° – 68° = 0.4673°). Multiply the fractional part of levels by 60 to convert to minutes. 68.4673° = 68° + 0.4673° = 68° (0.4673 x 60)′ = 68° 28.038′
Convert Decimal Degrees to Degrees Minutes Seconds (DMS)
First the fractional component of level is converted to decimal minutes as over to obtain the levels decimal minutes format. Then the decimal minutes is converted to minutes and secs. Comparable to above action totality minutes and also fractional component are separated, and fractional minute is converted to seconds by multiplying it by 60. Example - convert 68.4673° to levels minutes seconds: 68.4673° = 68° + 0.4673° = 68° (0.4673 x 60)′ = 68° 28.038′ 68° 28.038′ = 68° (28 + 0.038)′ = 68° 28′ (0.038 x 60)″ = 68° 28′ 2″ (secs rounded off, deserve to be preserved as decimal)
Convert Degrees Decimal Minutes to Decimal Degrees
The minute's part is converted to degrees and the outcome is added to the original entirety levels. Decimal Degrees = Degrees + (Minutes / 60) Example – convert 122° 35.483′ to decimal degrees: 35.483′ = 0.59138° 122° 35.483′ = 122° + (35.483 / 60)° = 122° + 0.59138° = 122.59138°
Convert Degrees Decimal Minutes to Degrees Minutes Seconds (DMS)
The decimal minutes part is converted to minutes and also secs. Whole minutes and fractional component are separated, and also fractional minute is converted to seconds by multiplying it by 60. Example – convert 43° 36.847′ to levels minutes seconds: 43° 36.847′ = 43° (36 + 0.847)′ = 43° 36′ (0.847 x 60)″ = 43° 36′ 50.8″
Latitude Longitude and Datum
A coordinate mechanism may be based upon different datums. Different maps might describe various datums, or the datum referenced by the GPS receiver might not correspond to the one for the map. For example older maps in North America are based on NAD 27 datum while recent maps are based upon NADVERTISEMENT 83. The default datum for GPS receivers is commonly initially collection to World Geodetic System of 1984 (WGS 84). And interactive maps such as Google Maps and also Bing Maps usage the WGS 84 datum.
Transferring coordinates in between map versions, GENERAL PRACTITIONERS and also map, or digital and also paper maps might cause errors in area of works with because of the misenhance of datums. For example transferring coordinates of a trail junction from a map based on NAD 27 datum to a GENERAL PRACTITIONERS that is set to WGS 84 datum may bring about the GENERAL PRACTITIONERS mirroring the place of the trail junction couple hundred meters off from the actual place.
It is crucial to state the datum as soon as functioning through geographical information. Guide publications normally specify the datum for the coordinates they administer. The datum in GPS receivers deserve to be set to correspond to the wanted map's datum. The datum is printed on the margin of topographic maps, sometimes together with indevelopment for conversion of coordinates in between two various datums by addition to or subtractivity from latitude and also longitude geographic coordinates; such as the instance to the ideal.
Example of adjust in datum in between map versions: http://www.nrdeserve to.gc.ca/earth-sciences/geography-boundary/mapping/topographic-mapping/10129.
Latitude longitude on map – place coordinates
Latitude and longitude (lat long) worths are usually noted on the margins of a map. Latitude and longitude lines might likewise be displayed as a grid across the map. Typically only the significant departments are labebrought about proccasion the cluttering of the map. Sub-divisions might only be labeled with partial coordinate values such as minutes or seconds. There is no one standard way of labeling latitude longitude lines on the map and its margins, and also tbelow have the right to be differences relying on the map scale, function of the map, and nation or locality of manufacturing.
Latitude longitude coordinate values on the map margins or a graticule across the map facilitate pinpointing the place of any kind of suggest given its coordinate values. Similarly geographical collaborates of any type of suggest on the map can be derived.
It need to be maintained in mind that huge range maps may cover areas that span much less than a degree of latitude and a degree of longitude. It is useful to inspect the 4 corners of the map to find the works with of the bounding area that is extended by the map, specifically when latitude longitude values are noted via partial numbers and also there is no grid on the map. Also the quadrant or the place with respect to the equator and prime meridian should be known once analysis worths on the map margin. For example in an area in north and western hemisphere such as USA or Canada, the latitude values increase from 0° at equator to 90° at north pole while longitude values go from 0 to -180° (the absolute number increases) traveling west. In southern and also eastern hemisphere, latitude worths go from 0° at equator to -90° (the absolute number increases) at south pole, and longitude values rise from 0° at prime meridian to 180° at International Date Line.
The map supplied in this instance is a 1:50000 topographic map of a region in British Columbia, Canada. The map sheet covers a room from 49°45′ N to 50°00′ N latitude and from 122°30′ W to 123° W longitude; the photo belongs to the lower best hand also edge of the map. In this map, the blue gridlines on the map and the blue consecutive numbers labeling each grid line are the UTM coordinates. Looking at the margins and the black numbers denoting geographical coordinates, it is evident that not eexceptionally level or minute is labeled; therefore it is necessary to study the labels to discover out the size of the divisions. In this map each of the alternating babsence and white bars on the margin represents 1′ of latitude running north-southern and 1′ of longitude running east-west.
Keep in mind that the grid lines or known margin departments of latitude and also longitude might be various in different maps. For instance latitudes may be split into 1′ sections and longitudes into 2′ intervals.
Find latitude longitude collaborates of a place on map
Based on the meaning of latitude and longitude, to discover the geographic coordinates of a allude on a map, the angular distance (north - south) of the allude relative to the equator and also its angular distance (east - west) family member to the prime meridian have to be identified.
In this example the geographic works with of the allude of incirculation of a stream right into Misty Lake from the southern, designated as point A is preferred. The first step is to discover out the nearest latitude and longitude entirety values approximately suggest A from the gridlines or in this situation from the margins of the map. The latitude longitude values of suggest A on the margin have the right to be noted by placing a right edge from allude A perpendicular to the margins. From the right margin it is clear that allude A is between 49°48′ N and 49°49′ N latitude, and the bottom margin shows the longitude of allude A to be in between 122°34′ W and 122°35′ W.
The latitude and also longitude worths of point A can be easily approximated by eyeballing their loved one position compared with the nearemainder bordering well-known latitude longitude values. Each bar deserve to be visually separated right into ten equal sections. Here allude A's latitude is halfmethod between 49°48′ N and 49°49′ N latitude. In various other words, its minute area is around 0.5′ better than 48′. Adding this angular distance to the lower latitude, suggest A's latitude would certainly be 49°48.5′ N. Similarly suggest A's longitude have the right to be approximated to be around 0.9 minutes higher than 122°34′ W, which deserve to be proclaimed as 122°34.9′ W.
A leader deserve to be offered in order to achieve more specific coordinate worths for the allude. Measuring the distance between the suggest noting the latitude of point A to the immediate recognized lower latitude worth, and also dividing this distance by the distance of the section in between reduced and higher latitude values bring about the proportional distance of point A from the known reduced worth. This distance is added to the lower latitude to provide the latitude of point A.
In this instance using a leader, allude A's latitude distance from the well-known lower latitude (49°48′ N) is 2.2cm. The distance between the reduced (49°48′ N) latitude and also greater (49°49′ N) latitude is 4.4cm. Here 1′ of latitude = 4.4cm. The proportional distance of A's latitude to reduced known latitude is 2.2 / 4.4 = 0.5. Converting this value to angular distance (in this instance angular distance in between the reduced and higher latitude is 1′ = 60″): 0.5 x 1′ = 0.5′ or 0.5 x 60″ = 30″. Adding this value to the reduced latitude offers the latitude of point A: 49°48.5′ N or 49°48′ 30″ N. Point A's longitude is calculated in the exact same fashion. Distance of A's longitude from known reduced longitude (122°34′ W) is 2.6cm. The size of the area in between reduced (122°34′ W) and also greater (122°35′ W) longitudes is 2.7cm. Here 1′ of longitude = 2.7cm. Proportional distance is 2.6 / 2.7 = 0.963cm. Converting this distance to angular distance: 0.963 x 1′ = 0.963′ or 0.963 x 60″ = 57.78″. Adding this value to the reduced longitude offers the longitude of allude A: 122°34.963′ W or 122°34′ 57.8″ W. Point A's geographical coordinate: 49°48′ 30″ N 122°34′ 57.8″ W.
Plot a point with well-known geographical coordinates
In order to locate a allude on a map offered its geographical works with, its latitude and longitude values should be noted on the margins or gridlines on map. The point deserve to then be placed at the cross section of right lines perpendicular to the margin originating from noted latitude longitudes. In this instance coordinates of point B are known: 49°46′21.8″ N 122°33′40″ W.
These worths have the right to be noted by eyeballing their family member position compared through the nearemainder surrounding well-known latitude longitude values. 21.8″ = 0.363′, therefore latitude of B deserve to be written as 49°46.363′ N. Visually dividing the bar right into ten sections (each would be 0.1′), and estimating the distance of 0.363′ or 0.4′ on the bar, it is basic to locate the position of the latitude on the margin. Similarly 40″ = 0.667′, so the longitude is 122°33.667′ W. And 0.667 or 0.7 have the right to be approximated on the bar after 122°33′ mark.
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A leader deserve to be used in order to pinsuggest these worths on the margins. 21.8″ = 0.363′, this fractivity of a minute can be converted to proportional distance in cm of a bar. A bar is 1′ and equal to 4.4cm, therefore the proportional distance is 0.363 x 4.4 = 1.597cm. The latitude of B deserve to be noted about 1.6cm to the north of 49°46′ N point. Similarly for longitude, 40″ = 0.667′, and 0.667 x 2.7 = 1.8cm, therefore the longitude of B have the right to be noted approximately 1.8cm to the west of 122°33′ W allude. Perpendicular lines to the edges of the map attracted from these points cross at suggest B.
Educational videos: arrival to lat long geographical coordinate system
http://www.youtube.com/watch?v=swKBi6hHHMA http://www.youtube.com/watch?v=-RVsZsK_r1c&feature=associated http://www.youtube.com/watch?v=EPL_e7iQ_Vo&feature=associated Circumnavigating the earth along the equator (latitude 0): http://www.youtube.com/watch?v=nQOWOJv3izs&feature=associated