Winds 1Wind intensity data at São Lourenço
Winds
Original title: Ventos
Entry on the winds of Madeira, reproducing wind frequency and intensity data observed at Ponta de São Lourenço in 1930–1932 from a study by naval officer C. Pinto Basto Carreiro, with an explanation of the trade winds.
1Wind intensity data at São Lourenço
Intensity and percentage frequency of the winds at Ponta de São Lourenço (‘St Lawrence Point’). From a study by the distinguished naval officer C. Pinto Basto Carreiro, we have taken the following interesting data:
PERCENTAGE INTENSITY OF THE WINDS OBSERVED AT SÃO LOURENÇO DURING THE YEARS 1930, 1931 AND 1932
| Direction | Light breezes (%) | Moderate (%) | Strong (%) | Stormy (%) |
|---|---|---|---|---|
| Light breezes | Moderate | Strong | Stormy | |
| N | 1 | 85 | 12 | 2 |
| NNE | - | 70 | 30 | - |
| NE | 0.8 | 84 | 15 | 0.2 |
| ENE | - | 75 | 25 | - |
| E | - | 89 | 11 | - |
| ESE | - | 83 | 17 | - |
| SE | - | 86 | 13.6 | - |
| SSE | - | 54.5 | 45.5 | - |
| S | - | 74 | 23 | 3 |
| SSW | - | 30 | 66 | 4 |
| SW | - | 46 | 50 | 46 |
| WSW | - | 39 | 53 | 80 |
| W | - | 76 | 23 | 1 |
| WNW | - | 78 | 22 | - |
| NW | - | 85 | 14 | 1 |
| NNW | - | 76 | 22 | 2 |
2Trade winds
The name trade winds (alizados) is given to the regular winds that blow steadily all year round on either side of the Equator, from the north-east towards the south-west in the northern hemisphere and from the south-east in the southern hemisphere.
In the North Atlantic the trade winds begin to be clearly felt on the island of Madeira, and sometimes even south of mainland Portugal. They blow steadily until close to the Equator.
Between the trade winds of the northern hemisphere and those of the southern hemisphere lies the zone of the equatorial calms. The counter-trade winds, or upper trade winds, blow in the high regions of the atmosphere in the opposite direction to the former.
3Frequency and intensity
Percentage of winds observed at São Lourenço during 1930, 1931 and 1932
The graph of the percentages of winds observed at São Lourenço shows that the prevailing winds are northerly, north-easterly and north-westerly. The least frequent winds are the ESE, SSE, WSW and WNW. The winds are observed at São Lourenço and not in Funchal, because the winds that affect the bay are not general, except when they belong to the southern quadrants. Of the southern quadrants, the most frequent winds are those from the SW and SE.
Intensity
The stormy winds are those of the southern quadrant, especially the S, SSW, SW and WSW. The greater percentage of these winds are strong.
The winds of the other quadrants are for the most part moderate. This is easily verified by looking at the attached scale’.
In this article
Time
Years mentioned · 01Place
Places mentioned · 03
Abroad
- Funchal
Winds affecting Funchal bay are local, so observations were made at São Lourenço instead.
The capital of the archipelago and seat of the principal captaincy, where settlement began; it was made a vila c.1451–52. Its bay, the widest in the archipelago, lies between Ponta do Garajau and Ponta da Cruz and offers sheltered anchorage, though its harbour had never been studied oceanographically. The Elucidário discusses it as a health resort with climate data and records the January 1906 disturbances, the Danish prince's visit in May 1846 and recent volcanic cones in the area.
- Ponta de São Lourenço
Machico. Site where the winds tabulated in the entry were observed in 1930–1932.
The Ponta de São Lourenço is the long, narrow eastern headland of Madeira in the parish of Caniçal, said to be named after the caravel São Lourenço, with a lighthouse on its islet. The Elucidário describes its geology, seasonal vegetation, islets, fossil calcareous bodies at Piedade, land snails and use as pasture. The steamer Forerunner sank there in 1884, and a submarine bank lies between it and the Desertas.
- Portugal
The trade winds are sometimes felt as far north as the south of mainland Portugal.
Portugal, the mother country of Madeira. The Elucidário notes that artillery detachments were sent from the mainland to garrison Madeira before 1877, that Madeira was linked to Portugal by telegraph cable in 1874, and that woad and gifts of honey were formerly sent there from the island. Mainland oranges and olives are compared favourably with those of Madeira and Porto Santo.
People
People mentioned · 01-
Portuguese naval officer whose study of winds at Ponta de São Lourenço supplied the data in this entry.