A COMPASS ROSE, sometimes called a WINDROSE, or ROSE OF THE WINDS, is
a figure on a compass , map , nautical chart , or monument used to
display the orientation of the cardinal directions : North, East,
South, and West—and their intermediate points. It is also the term
for the graduated markings found on the traditional magnetic compass .
Today, the idea of a compass rose is found on, or featured in, almost
all navigation systems, including nautical charts , non-directional
VHF omnidirectional range
The modern compass rose has eight principal winds . Listed clockwise, these are:
COMPASS POINT ABBR. HEADING TRADITIONAL WIND
North-East NE 45° (45°×1) Greco or Grecale
East E 90° (45°×2) Levante
North-West NW 315° (45°×7) Maestro or Mistral
Although modern compasses use the names of the eight principal directions (N, NE, E, SE, etc.), older compasses use the traditional Italianate wind names of Medieval origin (Tramontana, Greco, Levante, etc.)
4-point compass roses use only the four "basic winds" or "cardinal directions " (North, East, South, West), with angles of difference at 90°.
8-point compass roses use the eight principal winds —that is, the four cardinal directions (N, E, S, W) plus the four "intercardinal" or "ordinal directions " (NE, SE, SW, NW), at angles of difference of 45°.
16-point compass roses are constructed by bisecting the angles of the principal winds to come up with intermediate compass points, known as half-winds , at angles of difference of 22 1⁄2°. The names of the half-winds are simply combinations of the principal winds to either side, principal then ordinal. E.g. North-northeast (NNE), East-northeast (ENE), etc.
32-point compass roses are constructed by bisecting these angles, and coming up with quarter-winds at 11 1⁄4° angles of difference. Quarter-wind names are constructed with the names "X by Y", which can be read as "one quarter wind from X toward Y", where X is one of the eight principal winds and Y is one of the two adjacent cardinal directions. E.g. North-by-east (NbE) is one quarter wind from North towards East, Northeast-by-north (NEbN) is one quarter wind from Northeast toward North. Naming all 32 points on the rose is called "boxing the compass ".
The 32-point rose has the uncomfortable number of 11 1⁄4° between points, but is easily found by halving divisions and may have been easier for those not using a 360° circle. Using gradians , of which there are 400 in a circle, the sixteen-point rose will have twenty-five gradians per point.
A 4-point compass rose *
An 8-point compass rose *
A 16-point compass rose *
A 32-point compass rose
* 1 History
* 1.1 Classical compass rose * 1.2 Sidereal compass rose * 1.3 Mariner\'s compass rose * 1.4 Depiction on Nautical Charts
* 2 Modern depictions * 3 Usage * 4 In popular culture * 5 See also * 6 References * 7 External links
Linguistic anthropological studies have shown that most human communities have four points of cardinal direction . The names given to these directions are usually derived from either locally-specific geographic features (e.g. "towards the hills", "towards the sea") or from celestial bodies (especially the sun) or from atmospheric features (winds, temperature). Most mobile populations tend to adopt sunrise and sunset for East and West and the direction from where different winds blow to denote North and South.
CLASSICAL COMPASS ROSE
Main article: Classical compass winds
The ancient Greeks originally maintained distinct and separate systems of points and winds. The four Greek cardinal points (arctos, anatole, mesembria and dusis) were based on celestial bodies and used for orientation. The four Greek winds (Boreas, Notos, Eurus, Zephyrus) were confined to meteorology . Nonetheless, both systems were gradually conflated, and wind names came to eventually denote cardinal directions as well.
In his meteorological studies,
The Romans (e.g. Seneca , Pliny ) adopted the Greek 12-wind system,
and replaced its names with Latin equivalents, e.g. Septentrio,
Subsolanus, Auster, Favonius, etc. Uniquely,
According to the chronicler
The following table gives a rough equivalence of the classical 12-wind rose with the modern compass directions (Note: the directions are imprecise since it is not clear at what angles the classical winds are supposed to be with each other; some have argued that they should be equally spaced at 30 degrees each; for more details, see the article on Classical compass winds ). Classical 12-wind rose, with Greek (blue) and Latin (red) names (from Seneca)
WIND GREEK ROMAN FRANKISH
N Aparctias (ὰπαρκτίας) Septentrio Nordroni
NNE Meses (μέσης) or Boreas (βoρέας) Aquilo Nordostroni
NE Caicias (καικίας) Caecias Ostnordroni
E Apeliotes (ὰπηλιώτης) Subsolanus Ostroni
SE Eurus (εΰρος) Vulturnus Ostsundroni
SSE Euronotus (εὺρόνοtος) Euronotus Sundostroni
S Notos (νόtος) Auster Sundroni
SSW Libonotos (λιβόνοtος) Libonotus or Austroafricus Sundvuestroni
SW Lips (λίψ) Africus Vuestsundroni
W Zephyrus (ζέφυρος) Favonius Vuestroni
NW Argestes (ὰργέστης) Corus Vuestnordroni
NNW Thrascias (θρασκίας) Thrascias or Circius Nordvuestroni
SIDEREAL COMPASS ROSE
The "sidereal" compass rose demarcates the compass points by the
position of stars in the night sky, rather than winds.
"the Guards" (
NEbN Alpha Cassiopeiae
EbS Orion\'s belt
SEbE Beta Scorpionis
The western half of the rose would be the same stars in their setting position. The true position of these stars is only approximate to their theoretical equidistant rhumbs on the sidereal compass. Stars with the same declination formed a "linear constellation" or kavenga to provide direction as the night progressed.
A similar sidereal compass was used by Polynesian and Micronesian navigators in the Pacific Ocean, although different stars were used in a number of cases, clustering around the East-West axis.
MARINER\'S COMPASS ROSE
In Europe, the Classical 12-wind system continued to be taught in
academic settings during the Medieval era, but seafarers in the
Mediterranean came up with their own distinct 8-wind system. The
mariners used names derived from the Mediterranean lingua franca
—the Italian -tinged patois among Medieval sailors, composed
principally of Ligurian , mixed with Venetian , Sicilian , Provençal
, Catalan , Greek and
The exact origin of the mariner's eight-wind rose is obscure. Only
two of its point names (Ostro, Libeccio) have Classical etymologies,
the rest of the names seem to be autonomously derived. Two Arabic
words stand out: Scirocco (SE) from al-Sharq (الشرق – east in
Arabic) and the variant Garbino (SW), from al-Gharb (الغرب –
west in Arabic). This suggests the mariner's rose was probably
acquired by southern Italian seafarers not from their classical Roman
ancestors, but rather from Norman Sicily in the 11th to 12th
centuries. The coasts of the
The 32-point compass used for navigation in the Mediterranean by the
14th century, had increments of 11 1⁄4° between points. Only the
eight principal winds (N, NE, E, SE, S, SW, W, NW) were given special
names. The eight half-winds just combined the names of the two
principal winds, e.g. Greco-Tramontana for NNE, Greco-Levante for ENE,
and so on. Quarter-winds were more cumbersomely phrased, with the
closest principal wind named first and the next-closest principal wind
second, e.g. "Quarto di Tramontana verso Greco" (literally, "one
quarter wind from North towards Northeast", i.e. North by East), and
"Quarto di Greco verso Tramontana" ("one quarter wind from NE towards
N", i.e. Northeast by North).
Boxing the compass
DEPICTION ON NAUTICAL CHARTS
In the earliest Medieval portolan charts of the 14th century, compass roses were depicted as mere collections of color-coded compass rhumb lines : black for the eight main winds, green for the eight half-winds and red for the sixteen quarter-winds. The average portolan chart had sixteen such roses (or confluence of lines), spaced out equally around the circumference of a large implicit circle.
Cresques Abraham of
The points on a compass rose were frequently labeled by the initial
letters of the mariner's principal winds (T, G, L, S, O, L, P, M).
However, from the outset, the custom also began to distinguish the
north from the other points by a specific visual marker. Medieval
Italian cartographers typically used a simple arrowhead or
circumflex-hatted T (an allusion to the compass needle) to designate
the north, while the
Majorcan cartographic school typically used a
The twelve Classical winds (or a subset of them) were also sometimes depicted on portolan charts, albeit not on a compass rose, but rather separately on small disks or coins on the edges of the map.
The compass rose was also depicted on traverse boards used on board ships to record headings sailed at set time intervals.
Early 32-wind compass rose, shown as a mere collection of color-coded rhumblines, from a Genoese nautical chart (c. 1325) *
First ornate compass rose depicted on a chart, from the Catalan Atlas
(1375), with the Pole
More ornate compass rose, with letters of traditional winds and compass needle as north mark, from a nautical chart by Jorge de Aguiar (1492) *
Highly ornate compass rose, with fleur-de-lis as north mark and cross
pattée as east mark, from the
The contemporary compass rose appears as two rings, one smaller and set inside the other. The outside ring denotes TRUE cardinal directions while the smaller inside ring denotes MAGNETIC cardinal directions. TRUE NORTH refers to the geographical location of the north pole while MAGNETIC NORTH refers to the direction towards which the north pole of a magnetic object (as found in a compass ) will point. The angular difference between TRUE and MAGNETIC north is called variation , which varies depending on location. The angular difference between magnetic heading and compass heading is called deviation which varies by vessel and its heading.
IN POPULAR CULTURE
* Atlas portal
* ^ Patrick Bouron (2005). Cartographie: Lecture de Carte (PDF).
Institut Géographique National. p. 12. Retrieved 2011-07-07.
* ^ Brown, C.H. (1983) "Where do Cardinal Direction Terms Come
From?", Anthropological Linguistics, Vol. 25 (2), p. 121-61.
* ^ D'Avezac, M.A.P. (1874) Aperçus historiques sur la rose des
vents: lettre à Monsieur Henri Narducci. Rome: Civelli
Wikimedia Commons has media related to COMPASS ROSES .
* Origins of the