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Map of Earth  
Longitude (λ)  

Lines of longitude appear curved in this projection, but are actually halves of great circles.  
Latitude (φ)  
Lines of latitude appear horizontal in this projection, but are actually circular with different radii. All locations with a given latitude are collectively referred to as a circle of latitude.  
The equator divides the planet into a Northern Hemisphere and a Southern Hemisphere, and has a latitude of 0°.  File:World map with equator.jpg 
Latitude, usually denoted by the Greek letter phi (φ) gives the location of a place on Earth (or other planetary body) north or south of the equator. Lines of Latitude are the horizontal lines shown running easttowest on maps (particularly so in the Mercator projection). Technically, latitude is an angular measurement in degrees (marked with °) ranging from 0° at the equator (low latitude) to 90° at the poles (90° N or +90° for the North Pole and 90° S or −90° for the South Pole). The complementary angle of a latitude is called the colatitude and this is approximately the angle between straight up at the surface (the zenith) and the sun at the Spring and Fall equinox.
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All locations of a given latitude are collectively referred to as a circle of latitude or line of latitude or parallel, because they are coplanar, and all such planes are parallel to the equator. Lines of latitude other than the Equator are approximately small circles on the surface of the Earth; they are not geodesics since the shortest route between two points at the same latitude involves a path that bulges toward the nearest pole, first moving farther away from and then back toward the equator (see great circle).
.]] A specific latitude may then be combined with a specific longitude to give a precise position on the Earth's surface (see satellite navigation system).
Besides the equator, four other lines of latitude are named because of the role they play in the geometrical relationship with the Earth and the Sun:
Only at latitudes between the Tropics is it possible for the sun to be at the zenith. Only north of the Arctic Circle or south of the Antarctic Circle is the midnight sun possible.
The reason that these lines have the values that they do lies in the axial tilt of the Earth with respect to the sun, which is 23° 26′ 21.41″.
Note that the Arctic Circle and Tropic of Cancer are colatitudes, since the sum of their angles is 90°—similarly for the Antarctic Circle and Tropic of Capricorn.
A degree is divided into 60 minutes. One minute can be further divided into 60 seconds. An example of a latitude specified in this way is 13°19'43″ N (for greater precision, a decimal fraction can be added to the seconds). An alternative representation uses only degrees and minutes, where the seconds are expressed as a decimal fraction of minutes: the above example would be expressed as 13°19.717' N. Degrees can also be expressed singularly, with both the minutes and seconds incorporated as a decimal number and rounded as desired (decimal degree notation): 13.32861° N. Sometimes, the north/south suffix is replaced by a negative sign for south (−90° for the South Pole).
A region's latitude has a great effect on its climate and weather (see Effect of sun angle on climate). Latitude more loosely determines tendencies in polar auroras, prevailing winds, and other physical characteristics of geographic locations.
Researchers at Harvard's Center for International Development (CID) found in 2001 that only three tropical economies — Hong Kong, Singapore, and Taiwan — were classified as highincome by the World Bank, while all countries within regions zoned as temperate had either middle or highincome economies. ^{[1]} The validity of the Harvard report may be questioned because a different threshold is used for the tropical regions and the World Bank list fails to include Qatar's, United Arab Emirates', and Kuwait's economies. Further, countries such as Brazil have far better incomes than much of the Former Soviet Union and Iron Curtain states^{[citation needed]}.
Because most planets (including Earth) are ellipsoids of revolution, or spheroids, rather than spheres, both the radius and the length of arc varies with latitude. This variation requires the introduction of elliptic parameters based on an ellipse's angular eccentricity, $o\backslash !\backslash varepsilon\backslash ,\backslash !$ (which equals $\backslash arccos\backslash left(\backslash frac\{b\}\{a\}\backslash right)\backslash ,\backslash !$, where $a\backslash ;\backslash !$ and $b\backslash ;\backslash !$ are the equatorial and polar radii; $\backslash sin^2(o\backslash !\backslash varepsilon)\backslash ,\backslash !$ is the first eccentricity squared, $\{e^2\}\backslash ,\backslash !$; and $2\backslash sin^2\backslash left(\backslash frac\{o\backslash !\backslash varepsilon\}\{2\}\backslash right)\backslash ;\backslash !$ or $1\backslash cos(o\backslash !\backslash varepsilon)\backslash ,\backslash !$ is the flattening, $\{f\}\backslash ,\backslash !$). Utilized in creating the integrands for curvature is the inverse of the principal elliptic integrand, $E\text{'}\backslash ,\backslash !$:
n'(\phi)=\frac{1}{E'(\phi)} =\frac{1}{\sqrt{1(\sin(\phi)\sin(o\!\varepsilon))^2}};\,\!
M(\phi)&=a\cdot\cos^2(o\!\varepsilon)n'^3(\phi) =\frac{(ab)^2}{\Big((a\cos(\phi))^2+(b\sin(\phi))^2\Big)^{3/2}};\\ N(\phi)&=a{\cdot}n'(\phi) =\frac{a^2}{\sqrt{(a\cos(\phi))^2+(b\sin(\phi))^2}}.\end{align}\,\!
On Earth, the length of an arcdegree of north–south latitude difference, $\backslash scriptstyle\{\backslash Delta\backslash phi\}\backslash ,\backslash !$, is about 60 nautical miles, 111 kilometres or 69 statute miles at any latitude. The length of an arcdegree of eastwest longitude difference, $\backslash scriptstyle\{\backslash cos(\backslash phi)\backslash Delta\backslash lambda\}\backslash ,\backslash !$, is about the same at the equator as the northsouth, reducing to zero at the poles.
In the case of a spheroid, a meridian and its antimeridian form an ellipse, from which an exact expression for the length of an arcdegree of latitude difference is:
This radius of arc (or "arcradius") is in the plane of a meridian, and is known as the meridional radius of curvature, $M\backslash ,\backslash !$.^{[2]}^{[3]}
Similarly, an exact expression for the length of an arcdegree of longitude difference is:
The arcradius contained here is in the plane of the prime vertical, the eastwest plane perpendicular (or "normal") to both the plane of the meridian and the plane tangent to the surface of the ellipsoid, and is known as the normal radius of curvature, $N\backslash ,\backslash !$.^{[2]}^{[3]}
Along the equator (eastwest), $N\backslash ;\backslash !$ equals the equatorial radius. The radius of curvature at a right angle to the equator (northsouth), $M\backslash ;\backslash !$, is 43 km shorter, hence the length of an arcdegree of latitude difference at the equator is about 1 km less than the length of an arcdegree of longitude difference at the equator. The radii of curvature are equal at the poles where they are about 64 km greater than the northsouth equatorial radius of curvature because the polar radius is 21 km less than the equatorial radius. The shorter polar radii indicate that the northern and southern hemispheres are flatter, making their radii of curvature longer. This flattening also 'pinches' the northsouth equatorial radius of curvature, making it 43 km less than the equatorial radius. Both radii of curvature are perpendicular to the plane tangent to the surface of the ellipsoid at all latitudes, directed toward a point on the polar axis in the opposite hemisphere (except at the equator where both point toward Earth's center). The eastwest radius of curvature reaches the axis, whereas the northsouth radius of curvature is shorter at all latitudes except the poles.
The WGS84 ellipsoid, used by all GPS devices, uses an equatorial radius of 6378137.0 m and an inverse flattening, (1/f), of 298.257223563, hence its polar radius is 6356752.3142 m and its first eccentricity squared is 0.00669437999014.^{[4]} The more recent but little used IERS 2003 ellipsoid provides equatorial and polar radii of 6378136.6 and 6356751.9 m, respectively, and an inverse flattening of 298.25642.^{[5]} Lengths of degrees on the WGS84 and IERS 2003 ellipsoids are the same when rounded to six significant digits. An appropriate calculator for any latitude is provided by the U.S. government's National GeospatialIntelligence Agency (NGA).^{[6]}
Latitude  NS radius of curvature $M\backslash ;\backslash !$  Surface distance per 1° change in latitude  EW radius of curvature $N\backslash ;\backslash !$  Surface distance per 1° change in longitude  

0°  6335.44 km  110.574 km  6378.14 km  111.320 km  
15°  6339.70 km  110.649 km  6379.57 km  107.551 km  
30°  6351.38 km  110.852 km  6383.48 km  96.486 km  
45°  6367.38 km  111.132 km  6388.84 km  78.847 km  
60°  6383.45 km  111.412 km  6394.21 km  55.800 km  
75°  6395.26 km  111.618 km  6398.15 km  28.902 km  
90°  6399.59 km  111.694 km  6399.59 km  0.000 km 
With a spheroid that is slightly flattened by its rotation, cartographers refer to a variety of auxiliary latitudes to precisely adapt spherical projections according to their purpose.
For planets other than Earth, such as Mars, geographic and geocentric latitude are called "planetographic" and "planetocentric" latitude, respectively. Most maps of Mars since 2002 use planetocentric coordinates.
In common usage, "latitude" refers to geodetic or geographic latitude $\backslash phi\backslash ,\backslash !$ and is the angle between the equatorial plane and a line that is normal to the reference ellipsoid, which approximates the shape of Earth to account for flattening of the poles and bulging of the equator. This value usually differs from the geocentric latitude.
The expressions following assume elliptical polar sections and that all sections parallel to the equatorial plane are circular. Geographic latitude (with longitude) then provides a Gauss map. As defined earlier in this article, $o\backslash !\backslash varepsilon\backslash ,\backslash !$ is the angular eccentricity of a meridian.
&=\arcsin\!\left(\frac{\sin(\phi)\sin(o\!\varepsilon)n'^2(\phi)+\ln\Big(n'(\phi)\big(1+\sin(\phi)\sin(o\!\varepsilon)\big)\Big)}{\sin(o\!\varepsilon)\sec^2(o\!\varepsilon)+\ln\Big(\sec(o\!\varepsilon)\big(1+\sin(o\!\varepsilon)\big)\Big)}\right);\end{align}\,\!
=\frac{\pi}{2}\cdot\frac{\;\int_{0}^\phi\;n'^3(\theta)\,d\theta}{\int_{0}^{90^\circ}n'^3(\phi)\,d\phi};\,\!
A more obscure measure of latitude is the astronomical latitude, which is the angle between the equatorial plane and the normal to the geoid (ie a plumb line). It originated as the angle between horizon and pole star. It differs from the geodetic latitude only slightly, due to the slight deviations of the geoid from the reference ellipsoid.
Astronomical latitude is not to be confused with declination, the coordinate astronomers use to describe the locations of stars north/south of the celestial equator (see equatorial coordinates), nor with ecliptic latitude, the coordinate that astronomers use to describe the locations of stars north/south of the ecliptic (see ecliptic coordinates).
Continents move over time, due to continental drift, taking whatever fossils and other features of interest they may have with them. Particularly when discussing fossils, it's often more useful to know where the fossil was when it was laid down, than where it is when it was dug up: this is called the palæolatitude of the fossil. The Palæolatitude can be constrained by palæomagnetic data. If tiny magnetisable grains are present when the rock is being formed, these will align themselves with Earth's magnetic field like compass needles. A magnetometer can deduce the orientation of these grains by subjecting a sample to a magnetic field, and the magnetic declination of the grains can be used to infer the latitude of deposition.
The following plot shows the differences between the types of latitude. The data used are found in the table following the plot. Please note that the values in the table are in minutes, not degrees, and the plot reflects this as well. Also observe that the conformal symbols are hidden behind the geocentric due to being very close in value. Finally it is important to mention also that these differences don't mean that the use of one specific latitude will necessarily cause more distortions than the other (the real fact is that each latitude type is optimized for achieving a different goal).
Approximate difference from geographic latitude ("Lat")  

Lat $\backslash phi\backslash ,\backslash !$  Reduced $\backslash phi\backslash beta\backslash ,\backslash !$  Authalic $\backslash phi\backslash xi\backslash ,\backslash !$  Rectifying $\backslash phi\backslash mu\backslash ,\backslash !$  Conformal $\backslash phi\backslash chi\backslash ,\backslash !$  Geocentric $\backslash phi\backslash psi\backslash ,\backslash !$ 
0°  0.00′  0.00′  0.00′  0.00′  0.00′ 
5°  1.01′  1.35′  1.52′  2.02′  2.02′ 
10°  1.99′  2.66′  2.99′  3.98′  3.98′ 
15°  2.91′  3.89′  4.37′  5.82′  5.82′ 
20°  3.75′  5.00′  5.62′  7.48′  7.48′ 
25°  4.47′  5.96′  6.70′  8.92′  8.92′ 
30°  5.05′  6.73′  7.57′  10.09′  10.09′ 
35°  5.48′  7.31′  8.22′  10.95′  10.96′ 
40°  5.75′  7.66′  8.62′  11.48′  11.49′ 
45°  5.84′  7.78′  8.76′  11.67′  11.67′ 
50°  5.75′  7.67′  8.63′  11.50′  11.50′ 
55°  5.49′  7.32′  8.23′  10.97′  10.98′ 
60°  5.06′  6.75′  7.59′  10.12′  10.13′ 
65°  4.48′  5.97′  6.72′  8.95′  8.96′ 
70°  3.76′  5.01′  5.64′  7.52′  7.52′ 
75°  2.92′  3.90′  4.39′  5.85′  5.85′ 
80°  2.00′  2.67′  3.00′  4.00′  4.01′ 
85°  1.02′  1.35′  1.52′  2.03′  2.03′ 
90°  0.00′  0.00′  0.00′  0.00′  0.00′ 
When converting from geodetic ("common") latitude to other types of latitude, corrections must be made for altitude for systems which do not measure the angle from the normal of the spheroid. For example, in the figure at right, point H (located on the surface of the spheroid) and point H' (located at some greater elevation) have different geocentric latitudes (angles β and γ respectively), even though they share the same geodetic latitude (angle α). Note that the flatness of the spheroid and elevation of point H' in the image is significantly greater than what is found on the Earth, exaggerating the errors inherent in such calculations if left uncorrected. Note also that the reference ellipsoid used in the geodetic system is itself just an approximation of the true geoid, and therefore introduces its own errors, though the differences are less severe. (See Astronomical latitude, above.)
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From French latitude, from Latin lātitūdō (“‘breadth, width, latitude’”), from lātus (“‘broad, wide’”), for older stlatus.
Singular 
Plural 
latitude (plural latitudes)



[[File:thumb300pxMap of Earth showing some major latitudes]] The latitude of the Earth gives the distance north and south of the equator. It is measured in degrees. Latitude is represented by the Greek letter phi, $\backslash phi\backslash ,\backslash !$. It is usually used along with a measurement of longitude in order to pinpoint a location on Earth.
