Compass rose facts for kids

Kids Encyclopedia Facts
Modern nautical compass rose
A common compass rose as found on a nautical chart showing both true north and magnetic north with magnetic variation. Also notice the correspondence between the thirty-two point rose (inner circle) and the modern 0-360° graduations

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 beacons (NDB), VHF omnidirectional range (VOR) systems, global-positioning systems (GPS), and similar equipment.

The modern compass rose has eight principal winds. Listed clockwise, these are:

Compass point Abbr. Heading Traditional wind
North N Tramontane
North-East NE 45° (45°×1) Greco or Grecale
East E 90° (45°×2) Levante
South-East SE 135° (45°×3) Sirocco
South S 180° (45°×4) Ostro or Mezzogiorno
South-West SW 225° (45°×5) Libeccio or Garbino
West W 270° (45°×6) Ponente
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 us 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 2212°. 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 1114° 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 1114° 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.

History

Windrose
Compass rose with the eight principal winds

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.

Modern depictions

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.

Usage

  • NATO symbol uses four point rose.
  • Outward Bound uses the compass rose as the logo for various schools around the world.
  • An 8-point compass rose was the logo of Varig, the largest airline in Brazil for many decades until its bankruptcy in 2006.
  • An 8-point compass rose is a prominent feature in the logo of the Seattle Mariners Major League Baseball club.
  • Hong Kong Correctional Services's crest uses four point star.
  • The compass rose is used as the symbol of the worldwide Anglican Communion of churches.
  • A 16-point compass rose was IBM's logo for the System/360 product line.
  • A 16-point compass rose is the official logo of the Spanish National University of Distance Education (Universidad Nacional de Educación a Distancia or UNED).
  • A 16-point compass rose is present on the seal and the flag of the Central Intelligence Agency of the Federal government of the United States (the CIA).

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