The wind rose is the schematic representation of the cardinal points and the winds associated with each cardinal point meant as direction of origin (North, South, East, West) and the directions they mark out.
It is particularly used in meteorology since it concisely represents the distribution of wind speed by direction in a particular place.
It is a polar graph in which the points are coloured with bands corresponding to the classes of wind speed for each direction.
The length of the points changes depending on the wind frequency in each direction.
The simplest wind rose is that with 4 points formed by only the four cardinal points:
Four intermediate points can be established between the four cardinal points:
Therefore by listing clockwise the eight principal winds are:
| NORTH (N) | 0° | Tramontana north wind |
It is very intense and often in bursts, usually very cold or even frozen. Usually it anticipates dry weather and clear sky. |
| NORTHEAST (NE) |
45° | Grecale or Greco |
It blows from the north-eastern Balkans area although the name indicates an origin further south “from Greece”, due to the “Wind rose” position. Like the Tramontana north wind, it blows in bursts. It is a cold wind and brings dry weather. |
| EAST (E) | 90° | Levante east wind |
Its name indicates “where the sun rises”. It is rather weak and simply is an advance of the Scirocco and therefore an announcement of deteriorating weather. |
| SOUTHEAST (SE) |
135° | Scirocco south-east wind |
The name indicates its origins in Syria. It is a warm wind that creates rough seas and that it becomes very humid in the northern re- gions due to its passage over the Mediterranean sea. It indicates the arrival of rough weather. |
| SOUTH (S) | 180° | Mezzogiorno or Ostro south wind |
It is weak and on the Italian regions not very noticeable, except in the Adriatic sea. |
| SOUTHWEST (SW) | 225° | Libeccio south-west wind |
The name indicates its origin in Libya. It arrives rapidly, also reaching consider- able force. It drops suddenly and usually re- mains a situation of good weather. When its blowing is disturbing and dangerous for navigation: it causes a strong wave motion. |
| WEST (W) | 270° | Ponente west wind |
It indicates the sinking direction. It is more com- mon in summer and usually blows in the after- noon. It indicates, however, good weather. |
| NORTHWEST (NW) |
315° | Maestrale north-west wind |
The name refers to Rome, “Magistra” for the ancient people. It is a cold wind, stronger and more constant than the Tramontana. It sweeps away the clouds of disturbances and brings good weather, clear skies and dry weather. |
These four winds combined with those coming from the four cardinal points form the wind rose to 8 points.
Among the eight points identified above can indicate other eight, intermediate between the earlier, resulting a wind rose to 16 points.
The new eight points are clockwise: north-north-east, east-north-east, east-south-east, south-south-east, south-south-west, west-south-west, west-north-west and north-north-west.
The maximum extension of the wind rose is divided into:
In ancient times each compass had the image of a wind rose to 32 points on the background. The horizon was thus divided into thirty-second parts, which were called the fourth, they were used as the approximate unit during the approach manoeuvres (e.g. lay two fourths starboard). Due to the shape that is created in drawing them, they are also called rhombs.
Once in Italy, cartographic representations included a wind rose pointing to the cardinal points.
Today it is used to indicate the four cardinal directions and the component directions with (clockwise from North): N, NE, E, SE, S, SW, W, NW, then with the terms Tr (tramontana north wind), G (greco north-east wind) + (a cross pointed to the east), S (scirocco south-east wind), O (ostro south wind), L (libeccio south-west wind), P (ponente west wind), M (maestro north-west wind).