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Latitude
*** Shopping-Tip: Latitude
'''Latitude''', usually denoted symbolically by the Greek letter
phi (letter) φ, gives the location of a place on
Earth north or south of the
Equator. Latitude is an
angle angular measurement ranging from 0° at the Equator to 90° at the poles (90° N or 90° S).
'''Co-latitude''' is the
complementary angles complement of latitude.
Image:WorldMapLongLat-eq-circles-tropics-non.png thumb|300px|[[Map of
Earth showing lines of latitude, which appear straight and
horizontal in this projection, but are actually circular with different radii.]]
Lines of latitude
All locations of a given latitude are collectively referred to as a ''
line of latitude'' or ''parallel'', because they are
coplanar, and all such
Plane (mathematics) planes are
Parallel (geometry) 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 moving farther away from the equator. A specific latitude may then be combined with a specific
longitude to give a precise position on the Earth's surface. Certain lines of latitude are important such as the
Arctic Circle Arctic Circle Prime Meridian or
Antarctic circle.
Subdivisions
Each degree of latitude is further sub-divided into 60
minute of arc minutes (one minute of latitude is very close to one
nautical mile or 1852
metres), each of which divides into 60 seconds. A latitude is thus specified as '''13°19′43″ N'''. For high accuracy, the seconds are specified with a decimal fraction. An alternative representation uses degrees and minutes, where parts of a minute are expressed as a decimal fraction, thus: '''13°19.717′ N'''. Degrees expressed as a decimal number (decimal degree notation) is more often used: '''13.32861° N'''. Sometimes, the north/south suffix is replaced by a negative sign for south (−90° for the
South Pole).
Important latitudes
Latitudes of particular importance are the
Tropic of Cancer (latitude 23°27′ north), the
Tropic of Capricorn (latitude 23°27′ south), the
Arctic Circle (latitude 66°33′ north), and the
Antarctic Circle (latitude 66°33′ south). 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.
Effect of latitude
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.
Types of latitude
Because the
Earth is slightly flattened by its rotation, cartographers refer to a variety of auxiliary latitudes to precisely adapt spherical projections according to their purpose.
Common "latitude"
*In common usage, "latitude" refers to '''geodetic''' or '''geographic latitude''' φ and is the angle between the
equator equatorial plane and a line that is
Surface_normal normal to the reference
spheroid, which approximates the shape of the
Earth to account for flattening of the poles and bulging of the
equator.
The expressions following assume
ellipse elliptical polar sections with eccentricity ''e'', and that all sections parallel to the equatorial plane are circular. Geographic latitude (with longitude) then provides a
Gauss map.
Reduced latitude
*'''Reduced''' or '''parametric latitude''' β is the latitude of the same radius on the
sphere with the same equator.
::
Authalic latitude
*'''Authalic latitude''' ξ gives an area-preserving transform to the sphere.
::
Rectifying latitude
*Rectifying latitude μ is the surface distance from the equator, scaled so the pole is 90°. Unfortunately, it is an incomplete
elliptic integral:
::
Conformal latitude
*'''Conformal latitude''' χ gives an angle-preserving (
conformal) transform to the sphere.
::
Geocentric latitude
*The '''geocentric latitude''' φ
g is the angle between the equatorial plane and a line from the center of the
Earth.
::
For other planets such as
Mars (planet) Mars, geographic and geocentric latitude are called "planetographic" and "planetocentric" latitude, respectively. Most maps of Mars since
2002 use planetocentric coordinates.
{|border="1" cellspacing="0" cellpadding="4"
!colspan="6"|Approximate difference from geographic latitude
|-
!φ
!reduced
φ − β
!authalic
φ − ξ
!rectifying
φ − μ
!conformal
φ − χ
!geocentric
φ − φ
''g''
|-
|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′
|}
Astronomical latitude
*A more obscure measure of latitude is the '''astronomical latitude''', which is the angle between the equatorial plane and the
Surface_normal normal to the
geoid (ie a plumb line). It originated as the angle between horizon and pole star.
Latitude and wealth
It is frequently observed that there is a distinct correlation between latitude and the
wealth of nations. The continents along the
equator,
Africa and
South America are the poorest. Even within Africa and South America this can be seen as the nations furthest from the equator are wealthier. In Africa the wealthiest nations are the three on the southern tip of the continent,
South Africa,
Botswana, and
Namibia, and the countries of
North Africa. Similarly in Latin America
Argentina,
Chile and
Uruguay have long been the wealthiest. Within
Asia,
Indonesia, located on the equator, is among the poorest. The wealthiest nations of the world with the highest standard of living tend to be those at the northern extreme of areas open to human habitation,
Canada, and the
Nordic Countries. Within the wealthy continents, and even within large countries wealth increases with distance from the equator. Southern
Europe has long been poorer as has the Southern
United States.
There have been a number of explanations for this phenomenon. The first to describe and try to assess it was the
France French philosophe Charles de Secondat, Baron de Montesquieu Montesquieu who proposed that cold weather means less blood in the extremities, which makes the flesh less elastic; this gives northerners more strength and makes them less able to relax. This forcing of the blood inward, according to Montesquieu also means more flows through the heart, increasing vitality. These findings have been wholly discredited by modern science.
Evolutionary explanations
One explanation currently being promoted by supporters of
eugenics eugenics, is claimed to be grounded in
human evolution evolutionary theory. Some have argued that as humans
human migration migrated into higher latitudes and encountered colder weather there, the cold weather forced the evolution of higher group
intelligence (trait) intelligence by forcing inhabitants to perform more intellectually demanding tasks, such as building shelter, fires, and clothing, in order to survive (Lynn, 1991).
One study that supports this notion was performed by Beals et al. (1984, p. 309), who found a
correlation of 0.62 (
p-value p=0.00001) between latitude and
cranial capacity in samples worldwide and reported that each degree of latitude was associated with an increase of 2.5 cm³ in cranial volume.
Researchers such as psychologist
J. Philippe Rushton have argued that the association of greater brain size with greater latitude is due to the fact that cold weather imposes on its inhabitants more cognitively demanding tasks such as the need to construct shelter, make clothing, and store food.
Nevertheless, these explanations seem to be contradicted by the fact that it was in Africa, at near equatorial latitude, that harsh conditions such as extreme drought have brought our species, homo sapiens, to existence. Another contradicting observation is the high number of advanced civilizations that flourished near the equator -- such as Sumerian, Egyptian, Hindu among many others. The demanding tasks of shelter construction, cloth making and food storing, seem to be less likely to have constrained man's evolution since the invention of agriculture and writing.
Non-evolutionary explanations
Another explanation that is still widely held is that modern technologies and institutions were designed primarily in a small area of north western Europe. Thus agricultural techniques, machines, and medicines were designed to suit a temperate climate. These technologies and models readily spread to areas of similar climate, such as North America and Australia. As these areas also became centres of innovation this bias was further enhanced. Vastly less effort has been put into improving tropical agriculture than temperate because of this. Technologies, from automobiles to power lines are designed for colder drier regions and tend to work far worse in the tropics.
Thus, there exists a
feedback effect of technologies being designed for the wealthy, which makes them more wealthy and thus more able to fund technological development. One piece of evidence for this is that the far north has not always been the wealthiest latitude. Until only a few centuries ago, the wealthiest belt stretched from Southern Europe through the
Middle East, northern
India and southern
China. A dramatic shift in technologies beginning with ocean going ships and culminating in the
Industrial Revolution saw the most developed belt move north, in Europe, in China, and in the Americas. Northern Russia became a
superpower while southern India became impoverished and colonized. Such dramatic changes argue that the current distribution of wealth is not due to immutable factors such as climate or race. Evidence of this is that the agricultural revolution occurred first in ancient Mesopotamia.
Linked to this explanation is that of disease. The tropics are far more prone to devastating diseases due to their temperature that makes life easier on vectors such as insects and rodents. There has long been a
malarial belt spanning the
globe; this made human life more difficult. Most notably it was almost impossible for most forms of northern
livestock to thrive. The disparities have been compounded by the wealth of the north: vastly more research money goes into curing the ailments of northerners.
Physiologist
Jared Diamond, in his
Pulitzer Prize-winning work
Guns, Germs, and Steel, made the case that the
Europe-
Asia land mass is particularly favorable for the transition of societies from hunter-gatherer to farming communities. The continent stretches much further along the same lines of latitude than any of the other continents. As it is much easier to transfer a domesticated species along the same latitude than it is to move it to a warmer or colder climate, any species developed at a particular latitude will be transferred across the continent in a relatively short amount of time. Thus the inhabitants of this continent have a built-in advantage in terms of earlier development of farming, and a greater range of plants and animals from which to choose.
He also linked this progression to the development of diseases that were later to threaten the inhabitants of other continents. The close association of people in Europe-Asia with their domesticated animals provided a vector for the rapid transmission of diseases. Inhabitants of lands with few domesticated species were never exposed to the same range of diseases, and so, at least on the American continents, succumbed to diseases introduced from Europe.
Further reading
*John P. Snyder ''Map Projections: a working manual''
USGS
See also
*
Geographic coordinate system
*
Geodetic system
*
Geodesy
*
Great-circle distance
*
Horse latitudes
*
List of cities by latitude
*
List of cities by longitude
*
Longitude
*
Navigation
References
*{{cite journal | author=Beals, K. L., Smith, C. L. & Dodd, S. M. | title=Brain size, cranial morphology, climate, and time machines | journal=Current Anthropology | year=1984 | volume=25 | pages=301–330}}
*{{cite journal | author=Lynn, R. | title=The evolution of racial differences in intelligence | journal=Mankind Quarterly | year=1991 | volume=32 | pages=99–173}}
External links
-
GEONets Names Server, access to the
National Geospatial-Intelligence Agency's (NGA) database of foreign geographic feature names.
-
Look-up Latitude and Longitude
-
Resources for determining your latitude and longitude
-
Convert decimal degrees into degrees, minutes, seconds - Info about decimal to
sexagesimal conversion
-
Latitude and longitude converter – Convert latitude and longitude from degree, decimal form to degree, minutes, seconds form and vice versa. Also included a farthest point and a distance calculator.
-
NASS - Convert degrees/minutes/seconds to decimal degrees and vice versa -
JavaScript version
-
Worldwide Index - Tageo.com – contains 2,700,000 coordinates of places including US towns
**for each city it gives the satellite map location, country, province, coordinates (dd,dms), variant names and nearby places.
-
Distance calculation based on latitude and longitude - JavaScript version
* {{PDFlink}} [http://www.cia.gov/cia/publications/factbook/reference_maps/pdf/political_world.pdf Zoomable version of the map]
Category:Lines of latitude Lines of latitude
Category:Navigation
Category:Angle
af:Breedtegraad
ca:Latitud
cy:Lledred
da:Breddegrad
de:Breitengrad
el:ΓεωγÏ?αφικό πλάτος
es:Latitud
eo:Latitudo
fr:Latitude
he:%D7%A7%D7%95_%D7%A8%D7%95%D7%97%D7%91
it:Latitudine
mk:Латитуда
nl:Breedtegraad
ja:緯度
pl:Szerokość geograficzna
pt:Latitude
sk:Zemepisná Å¡Ãrka
sl:Zemljepisna širina
sv:Latitud
fi:Leveyspiiri
th:ละติจูด
zh:纬度
*** Shopping-Tip: Latitude