The climate of Egypt is generally very salubrious. The extraordinary dryness of the atmosphere (excepting in the maritime parts) is proved by the wonderful state of preservation in which bread, meal, fruits, &c., have been found in the tombs of ancient Thebes, after having been deposited there two or three thousand years. The ancient monuments of Egypt have suffered very little from the weather: the colours with which some of them are adorned retain almost their pristine brightness. There arises from the waters of the fields a considerable exhalation (though not often visible), during the inundation, and for some months afterwards; but even then it seems perfectly dry immediately within the skirts of the desert, where most of the monuments of antiquity are situated.[[11]]
The heat in Egypt is very great; but not so oppressive as might be imagined, on account of that extreme dryness of the atmosphere of which I have spoken, and the prevalence of northerly breezes.[[12]]
[11]. The damp at this period, slight as it is, occasions ophthalmia, diarrhœa, and dysentery, to be more prevalent now than at other times.
[12]. The general height of the thermometer (Fahrenheit’s) in Lower Egypt during the hot season, at noon, and in the shade, is from 90° to 100°; in Upper Egypt, from 100° to 110°; and in Nubia, from 110° to 120°, and even 130°, though in few years. In the latter country, if placed in the sand and exposed to the sun, the thermometer often rises to 150° or more. The temperature of Lower Egypt in the depth of winter is from 50° to 60°.
Rain is a very rare phenomenon in the valley of Egypt. In the Sa’eed, a heavy rain falls not oftener, on the average, than once in four or five years. My brother witnessed such an occurrence at Thebes, a tremendous storm of lightning and rain, in the autumn of 1827. Lightning is frequently seen, but thunder is seldom heard. On that occasion it was quite terrific, and lasted throughout a whole night. The torrents which pour down the sides and ravines of the naked mountains which hem in the valley of Egypt, on these occasions, though so rare, leave very conspicuous traces. Here, in Cairo, and in the neighbouring parts, there fall on the average four or five smart showers in the year, and those generally during the winter and spring. Most unusually (but this is in every respect an unusual season), it rained heavily on the night of the 30th of September. A heavy rain very rarely falls, and when it does, much damage is done to the houses. In the maritime parts of Egypt, rain is not so unfrequent.
The prevalence of the northwesterly wind is one of the most remarkable advantages of climate the Egyptians enjoy. The northwest breeze is ever refreshing and salubrious, beneficial to vegetation, and of the greatest importance in facilitating the Nile at almost every season of the year, and particularly during that period when the river is rising, and the current consequently the most rapid. During the first three months of the decrease of the river, that is, from the autumnal equinox to the winter-solstice, the wind is rather variable; sometimes blowing from the west, south, or east; but still the northerly winds are most frequent. During the next three months the wind is more variable; and during the last three months of the decrease of the river, from the vernal equinox to the summer solstice, winds from the south, or southeast, often hot and very oppressive, are frequent, but of short duration.
During a period called “El-Khamáseen,” hot southerly winds are very frequent, and particularly noxious. This period is said to commence on the day after the Coptic festival of Easter-Sunday, and to terminate on Whit-Sunday; thus continuing forty-nine days. It generally begins in the latter part of April, and lasts during the whole of May. This is the most unhealthy season in Egypt; and while it lasts the inhabitants are apprehensive of being visited by the plague; but their fears cease on the termination of that period. It is remarkable that we have already suffered much from the hot wind, for it is most unusual at this season. During July and August it was frequently distressing; and I can only compare it to the blast from a furnace, rendering every article of furniture literally hot, and always continuing three days. Having, happily, glass windows, we closed them in the direction of the wind, and found the close atmosphere infinitely more bearable than the heated blast. This was a season of extreme anxiety, being quite an unexpected ordeal for my children; but, I thank God, excepting slight indisposition, they escaped unhurt.
The “Samoom,” which is a very violent, hot, and almost suffocating wind, is of more rare occurrence than the Khamáseen winds, and of shorter duration; its continuance being more brief in proportion to the intensity of its parching heat, and the impetuosity of its course. Its direction is generally from the southeast, or south-southeast. It is commonly preceded by a fearful calm. As it approaches, the atmosphere assumes a yellowish hue, tinged with red; the sun appears of a deep blood colour, and gradually becomes quite concealed before the hot blast is felt in its full violence. The sand and dust raised by the wind add to the gloom, and increase the painful effects of the heat and rarity of the air. Respiration becomes uneasy, perspiration seems to be entirely stopped; the tongue is dry, the skin parched, and a prickling sensation is experienced, as if caused by electric sparks. It is sometimes impossible for a person to remain erect, on account of the force of the wind; and the sand and dust oblige all who are exposed to it to keep their eyes closed. It is, however, most distressing when it overtakes travellers in the desert. My brother encountered at Koos, in Upper Egypt, a samoom which was said to be one of the most violent ever witnessed. It lasted less than half an hour, and a very violent samoom seldom continues longer. My brother is of opinion that, although it is extremely distressing, it can never prove fatal, unless to persons already brought almost to the point of death by disease, fatigue, thirst, or some other cause. The poor camel seems to suffer from it equally with his master; and will often lie down with his back to the wind, close his eyes, stretch out his long neck upon the ground, and so remain until the storm has passed over.
Another very remarkable phenomenon is the “Zóba’ah,” and very common in Egypt, and in the adjacent deserts. It is a whirlwind, which raises the sand or dust in the form of a pillar, generally of immense height.[[13]] These whirling pillars of sand (of which my brother has seen more than twelve in one day, and often two or three at a time during the spring) are carried sometimes with great rapidity across the deserts and fields of Egypt, and over the river. My brother’s boat was twice crossed by a zóba’ah; but on each occasion its approach was seen, and necessary precautions were taken: both the sails were let fly a few moments before it reached the boat; but the boxes and cushions in the cabin were thrown down by the sudden heeling of the vessel, and every thing was covered with sand and dust.
[13]. “I measured” (says my brother) “the height of a zóba’ah, with a sextant, at Thebes, under circumstances which insured a very near approximation to perfect accuracy (observing its altitude from an elevated spot, at the precise moment when it passed through, and violently agitated, a distant group of palm-trees), and found it to be seven hundred and fifty feet. I think that several zóba’ahs I have seen were of greater height. Others which I measured at the same place were between five and seven hundred feet in height.”—Modern Egyptians, 3d Edition, Part I. chap. x.