Cardinal direction
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In geography, the four principal directional indicators are marked as points or arrowheads on a traditional magnetic compass rose. Called cardinal directions, they are north, east, south and west. Though the names may seem arbitrary, there are simple specific means to establish each direction, which should work anywhere on Earth where there is a view of the sky. North and south are oriented toward the respective poles of the Earth. The Earth's rotation defines the orientation of east and west.
A magnetised ferrous needle, allowed to move freely, aligns itself readily with the Earth's natural magnetic field. Upon aligning, the needle points reliably, but only approximately, in the directions we call north and south. This is the very basis of the magnetic compass. By an amazing coincidence the star Polaris is (for practical purposes) permanently pointed to by the earth's axis. We call the end of the Earth's axis that is closest to Polaris the North Pole. The opposite end of the Earth's axis is named the South Pole.
Due to the Earth's rotation, the sun rises during the morning in the east and sets during the evening in the west. (This definition of east and west is a matter of convention.)
With the cardinal points thus defined, by convention cartographers draw standard maps with north (N) at the top, and east (E) at the right. In turn, maps provide a systematic means to record where places are, and cardinal directions are the foundation of a structure for telling someone how to find those places.
North (N) does not have to be at the top. Portable GPS-based navigation computers can be set to display maps either conventionally (N always up, E always right) or with the current instantaneous direction of travel, called the heading, always up (and whatever direction is +90° from that to the right).
The direction of travel required to reach the intended destination is called the bearing. Since the real world presents numerous obstacles, one must adjust his or her heading accordingly. Upon moving forward, the bearing will change so that it always points at the destination, thereby giving clues as to which way one should turn. When you are traveling, it can be easier to figure out where your next turn is, and whether to turn left or right, when the direction of travel is always up.
The directional names are also routinely and very conveniently associated with the degrees of rotation in the unit circle, a necessary step for navigational calculations (derived from trigonometry) and/or for use with Global Positioning Satellite (GPS) Receivers. The four cardinal directions correspond to the following degrees of a compass:
- North (N): 0° = 360°
- East (E): 90°
- South (S): 180°
- West (W): 270°
An ordinal, or intercardinal, direction is one of the four intermediate compass directions located halfway between the cardinal directions.
- Northeast (NE), 45°, halfway between north and east, is the opposite of southwest.
- Southeast (SE), 135°, halfway between south and east, is the opposite of northwest.
- Southwest (SW), 225°, halfway between south and west, is the opposite of northeast.
- Northwest (NW), 315°, halfway between north and west, is the opposite of southeast.
There are also numerous additional intermediate points both named and numbered, a topic well addressed by Boxing the compass.
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[edit] Beyond Geography
Children are sometimes taught the order of these directions (clockwise, from North) by using a mnemonic, such as "Naughty Elephants Squirt Water", "Never Eat Soggy Waffles", or "Never Eat Shredded Wheat".
In mathematics, cardinal directions or cardinal points are the six principal directions or points of the 3D world in a solid.
In the real world there are six cardinal directions not involved with geography which are north, south, east, west, up & down.
[edit] Germanic origin of names
During the Migration Period, the Germanic languages' names for the cardinal directions entered the Romance languages, where they replaced the Latin names borealis (or septentrionalis), australis (or meridionalis), occidentalis and orientalis. See French language. It is possible that some northern people used the Germanic names for the intermediate directions. Medieval Scandinavian orientation would thus have involved a 45 degree rotation of cardinal directions.[1]
[edit] Cardinal directions in world cultures
Many cultures not descended from European traditions use cardinal directions, but have a number other than four. Typically, a “center” direction is added, for a total of five. Rather than the Western use of direction letters, properties such as colors are often associated with the various cardinal directions—these are typically the natural colors of human perception rather than optical primary colors. Some examples are shown here; for more (esp. with regard to American Indian tribes) see Colors of the Four Directions.
In many regions of the world, prevalent winds change direction seasonally, and consequently many cultures associate specific named winds with cardinal and ordinal directions. The classical Greeks personified these winds as Anemoi. The article on boxing the compass contains a more recent list of directional winds from the Mediterranean Sea.
[edit] Far East
| Asia | N | E | S | W | C | source |
|---|---|---|---|---|---|---|
| Ainu | [2] | |||||
| China | [3] [4] | |||||
| Kalmyks | N.A. | [5] | ||||
| Tibet | [2] | |||||
| Turkic | N.A. | [2] |
Traditional Chinese culture and some other Central Asian cultures view the center as a fifth principal direction. Each direction is often identified with a color, and geographical or ethnic terms may contain the name of the color instead of the name of the corresponding direction[3][4]. These traditions were also carried west by the westward migration of the Turkic peoples.
East: Green/Blue (青 "qīng" corresponds to green or blue); Spring; Wood
- Qingdao (Tsingtao) "Green Island": a city on the east coast of China
- Red River (Vietnam): south of China
- Red Sea: south of Turkey
- White Sheep Turkmen
- Ak Deniz "White Sea" in Turkish indicates the Sea of Marmara, the Aegean Sea, or the Mediterranean Sea
- Heilongjiang "Black Dragon River" province in Northeast China, also the Amur River
- Black Sea: north of Turkey
- Kara-Khitan Khanate
- Huangshan "Yellow Mountain" in central China
- Golden Horde: "Central Army" of the Mongols
[edit] Americas
| America | N | E | S | W | C | source |
|---|---|---|---|---|---|---|
| Apache | N.A. | [6] | ||||
| Aztec | N.A. | [7] [8] | ||||
| Cherokee | [2] [9] | |||||
| Lakota | [2] | |||||
| Mayan | [2] [7] | |||||
| Navajo | N.A. | [2] [6] | ||||
| Pueblo | N.A. | [2] [9] | ||||
| Sioux | N.A. | [2] |
In Mesoamerica and North America, many traditional indigenous beliefs include four cardinal directions and a center. Each direction was associated with a color, which varied between groups but which generally corresponded to the hues of corn (green, black, red, white, and yellow). There seems to be no “preferred” way of assigning these colors; as shown in the table, great variety in color symbolism occurs even among cultures that are close neighbors geographically.
[edit] Non-compass directional systems
Use of the compass directions is common and deeply embedded in European culture, and perhaps even more so in Chinese culture. Some other cultures make greater use of other referents, such as towards the sea or towards the mountains (Hawaii, Bali), or upstream and downstream (most notably in ancient Egypt, also in the Yurok and Karok languages).
[edit] See also
- azimuth
- Boxing the compass for the thirty-two principal points of the compass.
- Latitude and Longitude
- List of cartographers about famous cartographers through history
- Magnetic deviation to understand why a compass does not align perfectly with the earth's north and south poles.
- Orienteering to learn about an internationally popular hobby & sport that depends on the above knowledge for success.
- Uses of trigonometry
[edit] References
- ^ See e.g. Weibull, Lauritz. De gamle nordbornas väderstrecksbegrepp. Scandia 1/1928; Ekblom, R. Alfred the Great as Geographer. Studia Neophilologica 14/1941-2; Ekblom, R. Den forntida nordiska orientering och Wulfstans resa till Truso. Förnvännen. 33/1938; Sköld, Tryggve. Isländska väderstreck. Scripta Islandica. Isländska skällskapet årsbok 16/1965.
- ^ a b c d e f g h i Colors of the Four Directions. Retrieved on February 17, 2007.
- ^ a b Cardinal colors in Chinese tradition. Retrieved on February 17, 2007.
- ^ a b Chinese Cosmogony. Retrieved on February 17, 2007.
- ^ Krupp, E. C.: "Beyond the Blue Horizon: Myths and Legends of the Sun, Moon, Stars, and Planets", page 371. Oxford University Press, 1992
- ^ a b Symbolism of Color. Retrieved on February 17, 2007.
- ^ a b Aztec Calendar and Colors. Retrieved on February 17, 2007.
- ^ The Aztec Gateway. Retrieved on February 17, 2007.
- ^ a b Native American Quotes & Proverbs. Retrieved on February 17, 2007.
