October 31, 2010

A description of the rain

Abu Hatim tells us that Abu 'Ubayda said:
One day Al-Nu'man sallied forth after a rainstorm. On meeting with a mounted desert Arab on his camel, he hailed him, and the Arab obeyed his summons. Al-Nu'mān said: "How is the land that you have left behind you?" "Wide and spacious," said the Arab. "With easy lowlands, rugged hills and mountains firmly rooted, it is a capable sustainer of what sits on it." Al-Nu'mān said: "But I was asking you about the sky."

"It is high and free-standing," the Arab said, "without the aid of poles or tent-cords. Its day and night are clearly separated, and its sun and moon follow each other in succession." Al-Nu'mān said: "That's not what I’m asking you about!" "So ask what’s on your mind," the Arab said. Al-Nu'mān said: "Has rain been falling there, and if so can you describe it?" "Yes," the Arab said.

"The sky rained on our land for three long stretches without budging. It soaked it, left it swampy and then left it ankle-deep. Then I went forth from my people, and searched the land and found no part as far as Tish'ār that was spared. The clouds boomed out to one another on every side, and heavily the flow drave on, erasing the roads and filling the hollows, and digging the trees out at their roots. All souls kept to their shelters, and no traveler could depart until the sky left off harming us with its blessings. When solid land had re-emerged, and pathways through the fields could be descried, I came out to observe the sky and every quarter of its rim. No refuge could I find except for caverns in the hills, for the jarr al-dabu'* had been disgorged: the lowlands were like seas of slapping waves, the rugged hills were wrapped in flotsam, and carcasses of wild animals were flung in all directions. And I did not leave off treading the sky’s residue and wading its water until I reached your land."

*Abu Bakr said: The meaning of jārr al-dabu' ["The Hyena Driver"] is that it forces the hyena out of its underground lair.

Abu Bakr ibn Durayd, The Book of the Description of Rain and Clouds, ch. 14.

October 28, 2010

Al-Kindi on the rain, and why it seldom falls in Egypt

You ask (may God illuminate your pathway to the truth!) what causes some places to get hardly any rain. If the cause for abundance of rain in some places were to be made plain to you (may God guide you aright!), you might also appreciate (may God reveal to you all that is hidden!) the cause for a prevailing lack of rain in other places, since contraries are known together.

[...] All bodies undergo contraction when chilled, after which they need a smaller place than the one they occupied before their chilling. When heated, they undergo expansion, and need a larger place than the one they occupied before their heating. Therefore does air flow from a hot, expanded location toward one that is cold and contracted, and this flow is what we call the wind (for our usage gives the name of "wind" to the flow of air and "wave" to the flow of water). This explains why the wind is greatest when the sun's heat is shed along its southern inclination: expanded by that heat, air from the south flows north to where the air has been chilled by its remoteness from the sun.

When the sun is in its northern inclination it heats the areas to the north, and those in the south become chilled. The northern air then expands and flows in the direction of the south, due to the cold-induced contraction of the air there. For this reason, most summer winds are northerly winds, and most winter winds come from the south – except for winds which arise (in some cases all at once, in others little by little) from such sublunar factors as the course of rivers, the occurrence of floods, [and the influence of] stagnant waters, open meadows, the sun’s reflection on the tops of stony mountains, irrigation, agriculture, woods and wetlands. These factors (and others like them) contribute to the flow of vapor in different directions, which the various winds distribute according to the disposition of the earth’s territories (high places and low, caverns and open places), the influence of any fires burning therein, and so on.

The vapor made to flow across the face of the earth by the sun’s alternation between north and south was likened by ancient Greek sages to a freshwater sea of alternating tides, and they called it Okeanos, the earth-encircling sea.

When vapor ends up in a place whose distance from the sun’s path chills the air to the point that the vapor’s volume is reduced, the vapor becomes thick and dense and is converted into water by the air around it, which releases it in the form of rain upon the earth (along with any particles of earth taken up as earth-vapor). Meanwhile, these vapors crowd the air with their weight and set it moving, turning it into wind (which is the flow of air).

Vapor attains its maximum degree of density when it flows into caves or between mountains where its flow is hampered by the cold, or checked by an opposing flow of air, in the way that vapors have of being redirected by sublunar factors (as we have already described). But if vapor winds up in a location devoid of what reduces its volume and chills it, it spreads beyond that location until it encounters what we have defined as cold, condensing factors -- whether or not the land itself accumulates much standing water. For vapor is raised from the earth every day the sun casts it heat, and after it sets even more moisture may be released in the form of dew, having been attracted in the form of vapor that flows in from elsewhere, as happens daily in all forests.

As for those locations (be they in the south or elsewhere) whose moisture falls short, devoid as they are of any means of containing the vapor flowing into them from the south (due to the lack of high encircling mountains to the north) and furnished as they are with continual air currents (either by the influence of great quantities of moving water or the nearness of a body of water at its northern end), – locations in which the flow of vapor is diverted elsewhere due to some stronger flow prevailing against its wonted northward course – the presence of rain in those locations is very small. So it is in the country of Egypt, whose air on the north side lacks high mountains, and where most of the vapor flowing south to north (from the Sea of Abyssinia) is deflected by the mountains of the Beja (such as al-Muqattam and the mountains near it), so that the Sea of Abyssinia’s vapors flow towards Iraq.

From the treatise On why some places almost never get any rain

October 11, 2010

By the author of Aristotle Among the Arabs

I came into this world by chance, and by chance I will depart it. One proof of this is that if my father had not stooped to recover a blown sheet of paper that drifted to the ground one October day in 1913, he would have lost his life. On the evening of that day, an assassin hired by one of his enemies came near his seat in the mayoral house and fired a round of bullets at him. At that very moment, the sheet of paper he was reviewing (which was a brief from the shari'a court) took flight - and at the moment he bent over to retrieve it, the bullets buried themselves in the door behind him, grazing only the edge of his turban. "Is God alive?" he shouted, and fell silent. The assassin, believing he had dealt my father a fatal shot, took off running for his benefactor's house. My father recovered instantly, however, and ran off after him, keenly surmising that he would be led to the house of a wicked adversary called Gado Zarad. Along the way he called out for people to join him on the trail, and in half an hour they had Gado's house surrounded. Half the village turned out and stormed the house, and when they did not find the perpetrator one of their number led an attack on an unroofed house next door where he had fled. The man was found hiding in a corner and was seized and bound with ropes, as was the man who hired him. And my father sent word to the police in Fariskor (some 80 km from Sharabass), who came and took the men into custody and drove them back to the station in Fariskor. My birth took place 40 months later, on February 4, 1918.

If you examine the life of any person, you will find that a kind of chance is what gives rise to his or her birth, i.e. the chance encounter between the spermatazoa of a man and the egg cell in a woman. Whoever concludes from this that there is order or intentionality or a plan is just a dreamer. All that's at work are causes, operating in competition with each other, engendering whoever is engendered and annihilating whoever is annihilated.

'Abdel Rahman Badawi, The Story of My Life, v. 1, ch. 1.