Climate

Many physicians have considered the climate of Funchal capable of exerting a beneficial effect in the treatment of pulmonary diseases. Sir James Clark said that of all the climates known to him, that of Madeira was the best for persons suffering from pulmonary consumption. Dr Barral, in a work he wrote about this island, did not hesitate to recommend residence in Funchal *to individuals who, having a hereditary predisposition to tuberculosis, begin to suffer from a cough, or haemoptysis, or fatigue, or loss of weight, or any symptom that might give reason to fear the onset of that disease. According to the same physician, the climate of Funchal should also be recommended to all those suffering from incipient consumption or consumption in its first stage, and it may even be useful when the disease has reached the so-called second stage, provided that the patient feels strong and in good spirits. It was Dr Heberden who first gave a favourable account of the climate of Madeira, in 1751. He was followed by Dr Fothergill in 1755, Dr Adams in 1801, Dr Gourlay in 1811, Dr Nicolau Pita in 1812, Dr Heineken in 1824, Dr Sousa Vaz in 1832, Sir James Clark in 1835 and 1842, Dr Kampfer in 1847, Roberto White in 1851, Eduardo Harcourt in the same year, Dr Lund in 1853, Dr Barral in 1854, Dr Mittermayer in 1855, Dr Garnier in 1858, Dr Acursio G. Ramos in 1880, Dr Jacoud in 1881, Dr Embleton in 1882, Dr C. Taylor in 1889 and Dr Mourão Pita in 1859 and 1889.

It is true that Dr Mason did not approve of residence in Funchal for consumptives, and even sought to prove that the air here was more humid than in London. However, if we bear in mind that this physician’s observations were made in an exceptionally rainy year, and at one of the points in the city where the atmosphere is always more laden with water vapour, we are naturally led to conclude that such observations cannot be used to discredit our climate.

The frequency of tuberculosis among the natives is an argument often used by the detractors of our climate to drive away not only invalids but also those who visit us for other reasons. Yet although this frequency is a fact borne out by statistics, it does not seem to us that it can carry the significance some have sought to attribute to it. Alcoholism and other excesses, lack of hygiene and privation predispose people to tuberculosis here as everywhere else, and these are the chief reasons why one of the worst diseases afflicting humanity is so common on the island.

Dr Gourlay, in a work he published in 1811, advised consumptives to seek in Funchal a refuge from the winter of their own countries, even though he knew very well how much tuberculosis afflicted the natives. Dr Barral, whose integrity and knowledge of the subject no one can doubt, expressed himself as follows when speaking of the climate of the capital of Madeira: ‘the impression it makes on the traveller is of a gentleness and mildness so agreeable that it seems the most delicate and impaired constitutions could live there in the open air. In general, an almost uniform temperature, always moderate during the day; little wind, and that not troublesome; the hot hours tempered by a few clouds that soften the sun’s rays, and by the sea breeze (viração); never any notable cold; rains that are sometimes heavy but brief, soon leaving the ground fit for walking; an atmosphere in which one feels no humidity, nor dust, nor troublesome effluvia. All this at once shows the measure of an exceptional climate, suited to the treatment of chronic ailments in delicate constitutions. And on the man of the north who, fleeing the rigour of an inhospitable climate, lands there in winter and finds an extensive vegetation in full vigour, including many of the most beautiful and useful plants of every climate, it produces the marvellous effect of one of those paradises imagined and described by the poets. . . ’.

The data we present below sum up what is known about the climate of Madeira and confirm what has been said about the climate of Funchal. These data are indispensable to the physician and the physiologist, and may also be useful to the farmer and to those who intend to visit our country, whether for the benefit of their health or for any other reason.

Temperature. As a rule, Funchal has neither excessive cold nor excessive heat. The temperature in the shade rarely falls below 8 °C or rises above 26 °C, and only on days of leste (hot, dry easterly wind from Africa) does the thermometer here record somewhat high temperatures. The slight variation in warmth from month to month and from season to season is one of the characteristics of Funchal's climate; it should also be noted that the temperature does not change greatly during the day. The highest temperatures are observed between 1 and 3 p.m. and the lowest between 4 and 6 a.m. In other words, the greatest thermal fluctuations of the day are scarcely felt by invalids, who rarely go out into the open air before 8 or 9 a.m. or after 7 or 8 p.m. The observations made at the Funchal Meteorological Station over a period of 9 years (1901–1909) give the following results for the mean temperature of Funchal, in degrees centigrade:

Month	Mean temperature (°C)
January	15.00
February	14.92
March	15.35
April	16.24
May	17.32
June	19.16
July	20.78
August	22.19

Month	Mean temperature (°C)
September	21.47
October	19.97
November	17.50
December	15.80

The mean temperature over this period was 17.97, and if we take the difference between the highest and lowest of the monthly means (22.19 and 14.92), we find 7.27. The absolute maximum was 37.3, on 13 August 1907, and the absolute minimum 4.5, on 25 February 1904, a difference, therefore, of 32.8. The mean of the annual means was 18.61 from 1865 to 1893, and 18.67 from 1865 to 1874. As regards the seasons of the year, their mean temperatures from 1901 to 1909 were as follows:

Season	Mean temperature
Winter	15.24
Spring	16.30
Summer	20.71
Autumn	19.64

The Englishman White, who made meteorological observations at Machico and at Santo António da Serra from June to September 1850, found the following mean temperatures for those places:

MACHICO SANTO ANTÓNIO DA SERRA

Month	Mean temperature
June	19.35
June	17.03
July	21.10
July	18.03
August	21.16
August	18.40
September	21.12
September	-

The mean temperature at Poiso (1,400 m) was 13.4° in the months of July to November 1904, and at Areeiro (1,700 m) 12.2° in the months of June to October 1895. Mr Guilherme Teles de Meneses, to whom these meteorological observations are owed, saw the thermometer at Areeiro register 2 degrees below zero in November 1895, and we read in Excursões na Madeira, by the late Father Pontes, that when the temperature in Funchal is 14 degrees centigrade, the thermometer on the Paul da Serra (‘upland marsh’) sometimes stands at zero or below.

The following table, taken from the observations made by Mr Adolfo César de Noronha, shows the mean temperature in the shade in the town (vila) of Porto Santo (15 m above sea level) from December 1900 to November 1901 and from June to December 1902:

Month	Mean temperature
December	18.6
June	21.3
January	17.3
July	22.5
February	17.4
August	24
March	17.9
September	23.8
April	19
October	21.7
May	20.1
November	20

The highest temperature observed during this period was 29.2°, on 24 August 1902; the lowest was 12, on 10 January 1901. These temperatures, and especially the latter, should not be regarded as absolute extremes, since the observer did not use a maximum and minimum thermometer in his observations.

The greatest strength of the sun in Funchal, says Dr Mason, usually occurs from 0 to 11 a.m., and more than once during 1907 we had occasion to note that on clear days thermometers exposed to the sun register higher temperatures at noon than at 3 p.m. According to Dr Mason, the greatest absolute strength of the sun is 761, 11 centigrade and the mean maximum 466.96, the seasonal means being as follows: winter 34.90; spring 49.50; summer 56.11; and autumn 47.35. In August 1907, during a leste and with a clear sky, we saw the thermometer at the São Lourenço station register 62.5 in the sun at noon, and 59.2 at 3 p.m.:

Atmospheric pressure. The meteorological observations made at the São Lourenço station from 1901 to 1909 yield the following averages for atmospheric pressure:

Month	Mean atmospheric pressure
January	765.71
July	763.98
February	765.51
August	763.43

Month	Mean pressure
March	763.60
September	763.46
April	762.81
October	761.86
May	762.75
November	761.90
June	762.95
December	763.61

Season	Mean pressure
Winter	764.94
Summer	763.45
Spring	763.05
Autumn	762.40

The lowest atmospheric pressure observed in Funchal to date, 737.61, occurred on 23 January 1868 in calm weather, although on that day a violent gale struck Tenerife and brought down the famous dragon tree of the Orotava valley. According to Mr Teles de Meneses, the mean pressure at Poiso was 636 mm in the months from July to November 1894, and at Areeiro 617.5 in the months from July to October 1895.

The observations made by Mr Adolfo de Noronha in the town (vila) of Porto Santo from 1 June to 9 December 1902 gave the following averages:

Month	Mean pressure
June	763.46
July	763.20
August	761.61
September	762.31
October	762.32
November	763.12
December	761.15

The difference between the absolute maximum of 768.40 (24 November) and the absolute minimum of 752.83 (3

November) was 15.67.

Humidity. In Funchal humidity is so closely bound up with temperature that it never appears as mist, nor is it troublesome to those exposed to it. Invisible as it is, this humidity nevertheless plays an important part in the island’s climatic conditions, since it tempers the harshness of the air and prevents the extremes of temperature to which regions in the interior of continents are subject.

Between 800 and 1000 metres on the south side of Madeira, and between 700 and 800 on the north side, dense fogs are often seen wrapping the mountains, chiefly during the day, because thermal conditions there become unfavourable to keeping water in a clear vapour state. Above and below these altitudes, however, humidity changes gradually, and at an altitude of 1700 metres it is already slight.

The greatest dryness is observed when the leste (hot, dry easterly wind from Africa) blows; relative humidity may then fall as low as 18 per cent, as Mac Euen noted on 17 February 1849 at Quinta Holloway (‘Holloway estate’), about 85 metres above sea level.

Month	Relative humidity
	Relative humidity
January	62.2
February	62.7
March	57.5

Month	Relative humidity
April	61.3
May	61.5
June	65.1
July	66.3
August	63
September	62.3
October	63.4
November	65.3
December	64.6

Highest monthly mean over the 5 years: 68.9 (October 1904). Lowest monthly mean over the 5 years: 55.6 (March 1902). Mean for the 5 years: 62.9. Seasonal means: winter 63.1; spring 60.1; summer 64.8; autumn 61.6.

Vapour tension
Month	Vapour tension
January	8.97
February	9.08
March	8.51
April	9.56
May	9.99
June	11.85
July	13.59
August	13.92
September	13.20
October	11.95
November	10.86
December	9.70

Highest monthly mean during the 5 years: 14.14 (August 1904). Lowest monthly mean during the same period: 7.77 (March 1904). Mean for the 5 years: 10.93.

According to White, the mean relative humidity at Santo António da Serra was 76% in June and July 1850 and 72% in August of the same year; and according to Mr Teles de Meneses, it was 58.8% at Poiso and 65.6% at Areeiro in the periods mentioned above.

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Relative humidity in Funchal’, says Mr Teles de Meneses, ‘is generally higher in the afternoon and lower in the morning; at Areeiro it is exactly the reverse. As the sun rises above the horizon, the clouds condensed far below this zone rise through the expansion of the warmed air, and for this reason humidity increases at around 7 in the morning, decreasing from 9 onwards until the same hour the next day. At Areeiro the air in the afternoon is so dry that in calm weather one can stay outdoors until 11 at night and later without experiencing the slightest discomfort.

The following data show the mean relative humidity in the town of Porto Santo from June to December 1902:

Month	Mean relative humidity
June	70.2
July	72.2
August	67.3
September	71.1
October	70
November	76
December	76.1

Rain. Rain falls in every month of the year in the uplands of Madeira, but in Funchal it is sometimes absent, especially during the summer. The first heavy rains generally arrive in October, and from then until April it rains more or less abundantly in Funchal, although the precipitation does not follow a clearly marked periodic pattern. In May and June there is sometimes a lack of rain, and in July and August, in certain years, not a single drop of water falls in Funchal. The autumn rains are as a rule heavier and more violent than those of winter.

It is rare, Dr Barral reports, for it to rain in the city all day or all night; there are generally intervals in which no rain falls at all, and the weather may even turn clear during these intervals. Torrential rains are brought by the south-west, north-east and west winds, and sometimes last several days, though with varying intensity.

The averages we give below refer to the quantity of rain, in millimetres, collected by the rain gauge of the Funchal Meteorological Station in the period from 1901 to 1909:

Month	Rainfall (mm)
January	78.3
February	79.8
March	58.8
April	33.4
May	21.4
June	16
July	2.9
August	6.7
September	20.4
October	97.4
November	137.3
December	85.4

In 1901, a very wet year, 1138 mm of rain fell in Funchal; in 1906, a very dry year, only 488 mm. In June 1904, in July 1903, 1905 and 1909, and in August 1901, 1903, 1905, 1906, 1908 and 1909, no rain at all fell in Funchal. The greatest daily rainfall was 155.1 mm, on 10 November 1901.

In Funchal it rains on average on 79 days a year; the largest number of rainy days recorded to date in a single year is 101, and the smallest 52. From December 1900 to November 1901 Porto Santo had 40 days of heavy rain and 84 of light rain, or drizzle.

Snow, frost and hail. These forms of precipitation occur in the uplands of Madeira, as we shall describe elsewhere.

(See

Dente de cão (‘dog’s tooth’, popular name for crystalline hoar frost), Hail and Snow)

Clouds and fogs. ‘In Madeira,’ says Dr Barral, ‘there are a good number of clear days on which the sky is pure and almost cloudless; but there is a greater number of clear days, with excellent weather, on which clouds appear during the day in greater or lesser numbers – cumulus and cirrus – showing themselves now, then vanishing at once, cooling the temperature and blocking the sunlight for short spells… There are not many days on which the sky stays overcast without the sun being visible at any time of the day, but there are many on which the sun is not seen for hours, the day being clear and the weather fine before and after… A clear and serene atmosphere, with a resplendent, luminous and pure sky, such as is often seen in the climates of Italy, especially southern Italy, is very seldom observed in Madeira…’

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In the morning,’ the same author goes on, ‘the mountain tops appear clear, while the horizon over the sea is laden with heavy, thick, dark clouds, nimbus, or else white, towering clouds, more or less separate from one another, cirrus, cumulus, rise above the Ocean. The sea breeze drives them over the land for part of the day, cooling the air and tempering the heat of the sun’s rays; towards evening the sky is overcast. The wind then shifts to the northern quarter, usually between north and north-east, and carries the clouds out to sea; many of them spread out and disperse with the wind. The nights are very often clear, especially until midnight, and the stars shine with a tropical brilliance: and this is repeated for many days, the said changes taking place at almost the same hour every day. On some nights, too, a light mist can be seen over the sea or over the mountains, and the lunar rainbow is not a very rare phenomenon there. By day it is a frequent phenomenon, and sometimes one of great beauty.

The fogs that girdle the mountains in the condensation zone, which we have already discussed above, come from the vapour carried by the rising air currents that form along the slopes during the day. These fogs often disappear at nightfall, leaving the nights clear and starry. In summer the fogs form lower down than in winter, so that the zone of greatest humidity lies higher in winter than in summer.