Aristotle · a new plain-English translation from the original language
1| Book 26. Problems Concerning Winds.
2| Why is the caecias the only wind that draws the clouds toward itself? Is it because it blows from higher regions? For the regions toward the east are higher than those toward the west. A sign of this is the size and depth of the sea toward the west. Blowing as it does from above, against the opposite direction, it makes, in its course, a line whose concave side faces the earth. Striking, as has been said, the western regions of the earth, and contracting the clouds because of the shape of this line, by the rebound from there it pushes them back toward itself. It alone of the other winds does this, because for the rest the regions from which they come are either higher or lie opposite, so that the motion from below happens to occur toward them in a straight line, the course having its convex side toward the earth, with the result that no rebound of the wind occurs, because a course that does not have its concave side toward the earth has, as the end of its motion, air in which there are no clouds near the earth; and for the less concave winds, and for the apeliotes, the reason is that it is not moist. So, since it does not condense clouds, it is less evident that it is doing what it does.
3| Why do north winds occur as seasonal (etesian) winds, but not south winds? Or do south winds occur too, but not continuously, because the source of the south wind is far from us, while we live under the north? Further, the etesian north winds blow when the air is settled (for they blow in summer), while south winds blow in spring, when conditions in the air are less settled. Besides this, the south wind is moist, and the region above is alien to moisture; hence the moist matter forming within it is quickly dissolved. And moist things wander, so that, not staying in the same place, it shifts along with itself the motion of the air too. And when the motion is not in the same place, it happens that other winds arise; for wind is motion of air. Why does the south wind blow after frost? Is it because frost occurs when concoction is taking place, and after the concoction and the purging the change is to the opposite? And the south wind is opposite to the north. For the same reason the south wind blows after snow as well. In general, snow, hail, rain, and every such purging is a sign of concoction. Hence too, after rain and storms of that kind, the winds die down.
4| Why do the reversing winds blow? Is it for the same reason that tidal straits flow back? For up to a point both the sea and the air are carried along in the flow; then, when it meets resistance and the land-breezes can no longer advance further, because they do not have a strong source of motion and carrying, it gives back again in the opposite direction. Why do the reversing winds come from the sea? Is it because the sea is near? Or because the reversing wind is opposite to the land-breeze, and the reversing wind is, as it were, a turning-back of the land-breeze? The land-breeze is the wind that arises from the land toward the sea, and the reversing wind is the ebb-flow of this. So it must come from the sea. [Or is the sea the cause] because the air that has flowed collects into the sea? And the cause of its not gathering instead into the land, and of its bending back as it departs, is that the sea lies in a hollow; and air, like water, always flows into the most hollow place. Why do storm-squalls die out sooner once rain has occurred? Is it because the cavities of the cloud, in which the source of the wind is formed, collapse once rain has occurred?
5| Why are not the same winds rain-bringing everywhere? Is it because the same winds do not everywhere blow against mountains, but different winds lie opposite different mountains? For where winds flow with difficulty against a rising slope, there the clouds settle more, at the point where the wind is no longer able to push them further forward. And settling there and being compressed, they burst. Why are clear sunsets a sign of fair weather, and disturbed sunsets a sign of storm? Is it because storm occurs when the air is condensing and thickening? So when the sun prevails, it separates the air out and makes it clear, but when it is overpowered, it makes it clouded. If, then, the condensation is strong, storm occurs immediately, by day; but if it is weaker, and not altogether overpowered, what is condensing is pushed out toward sunset. And it stays there because the air around the earth is thickest in winter. The rest of the air also quickly condenses, because it has a starting point and a support to receive and gather what is coming in, just as happens at daybreak; for just as in a rout, when one man stands his ground the others also stay, so too with the air. Hence clouding-over sometimes happens quickly and suddenly. So when sunsets are disturbed, it is a strong sign that the sun has not overpowered the condensation, though opposing it for a long time, so that it is reasonable that more should condense. And it is less alarming when this happens after a storm has already occurred than when it happens out of fair weather. For in the former case it seems to be, as it were, a remnant of something, while in the latter it is the beginning of a condensation.
6| Why is it said, "never has a north wind by night reached a third daylight"? Is it because winds from the north are weak when they occur by night? For it is a sign that the air set in motion is not much. The sign is that it blew at a time when there was little heat present; and little heat set little air in motion. And all such things come to an end within three days, the least of them within the first triad, so this wind too ends within that span. Why does the north wind blow more often than the south? Is it because the north wind, being neighbor to the inhabited world, does not go unnoticed even when short-lived (for it is present as soon as it blows), while the south wind often does not reach us at all, because it blows from far off? Why does the south wind blow less after winter nights than after winter days? Is it because even by night the sun is near the region toward the south, and the nights there are warmer than the days are toward the north? So a great deal of air is set in motion, no less than by day; but the warmer days hinder it from blowing more, by drying up the moisture.
7| Why does the south wind blow at the rising of the Dog-star, and does this happen in an orderly way, as with other things? Is it because the lower regions are hot, the sun being far off, so that much vapor arises? And indeed many winds would blow then, were it not for the etesian winds. As it is, these prevent it — or is it rather because the weather gives signs at the setting or rising of every star, and not least at this one? And it is clear that winds occur most of all at this rising and after it. And since it is stifling then, it is reasonable that the hottest winds should be set in motion at that time; and the south wind is hot. And since it is most usual to change from opposites into opposites, and before the Dog-star the forerunner winds that blow are north winds, it is reasonable that after the Dog-star the south wind blows, since the sky gives its sign at the risings of the stars. And to give a sign is to produce a change in the air; and all winds change into their opposites or into the winds on the right. And since the north wind changes into the winds on the right, it would remain for it to change into the south wind. The fifteenth day after the winter solstice is also a day of south wind, because the solstice is a kind of starting point, and the sun most sets in motion the air that belongs to it at that time, and at this solstice the sun is toward the south. So just as, by setting in motion the air from the east, it stirs up east winds, so too, by setting in motion the air from the south, it stirs up south winds. It does not produce this effect immediately from the solstice, because the changes it makes then are very slight, but on the fifteenth day, because that span of time is proportionate to the first appearance of the change; for the period mentioned is the most clearly marked part of the whole.
8| Why is it especially in the time of Orion that the days are variable and the winds untimely? Is it because in a period of change everything is always most indefinite, and Orion rises at the beginning of autumn but sets in winter, so that, because a single season has not yet become established, but one is coming into being while the other is ceasing, for this reason the winds too must necessarily be unsettled, because the winds from each of the two seasons pull both ways at once? And indeed Orion is called difficult both at its setting and at its rising, because of the indefiniteness of the season; for it must necessarily be turbulent and irregular. Why does the north wind by night stop on the third day? Is it because it starts from a small and weak beginning, and the third day is critical? Or is it because its outflow is sudden, as with squalls, so that its cessation too is quick? Why do north winds blow more often than the other winds? Is it because the inhabited world lies exposed to this quarter, which is high, outside the tropics, and full of snow, which never leaves some of its mountains? So it is chiefly from the melting of what has frozen that wind is often produced. And this is the north wind, the wind that comes from the regions toward the Bear.
9| Why do south winds blow in winter, at the beginning of spring, and at the end of autumn, and why are they wave-raising and gathered together, and, for the people in Libya, just as cold as north winds are here? Is it because, when the sun is near, the winds must necessarily be set in motion? And the sun in winter moves toward the south, and warms the region as spring is beginning and as autumn is ending, while in summer it moves toward the north and leaves those regions behind. And the wind is hot because it mixes with the air over Libya, which is hot; and because of this the summer, falling upon the sea, makes it swell with great waves and turn southerly. Why is the south wind foul-smelling? Is it because it makes bodies moist and hot, and such bodies decay most readily? But south winds off the sea are good for plants, since they reach the plants from the sea. And this is the cause for the Thriasian plain in Attica, because the wind arrives there cooled. Blight arises from moisture that is hot, but foreign to the plant. Why does wind generally arise before eclipses — a wind at dusk before eclipses at midnight, and a wind at midnight before eclipses at dawn? Is it because the heat from the moon grows dim as its course draws near the point at which the eclipse will occur? So, as the air, which had been held in check and was still, is released, it moves again and wind arises, and the later the eclipse, the later this wind occurs.
10| Why is the south wind not rainy at its beginning but at its ending? Is it because it gathers the air together from far off? And the rain is produced when the air is condensed, and it is condensed later than the wind begins. Or is it because at its beginning the air is still hot, from having come from such a source, but as time passes it cools and condenses more into water? Why is the south wind clear when it is small, but cloudy and longer-lasting when it is great? Is it, as some say, because of its origin — if it starts from a smaller source it is clear, but if it sets out from a larger one it is cloudy? Or is it because it is small at its beginning, so that it pushes little air, but toward its end it tends to become great? This is also why they have the saying: south wind at its beginning, north wind at its ending. Why do the winds set out from the east in winter but from the west as well in summer? Is it because, when the sun no longer dominates, the air, being released, flows? So, as the sun sets, it leaves clouds behind, from which the west winds come; and whatever it draws along toward those who live in the lower hemisphere becomes, for them, a morning wind. And the opposite happens when it sets in the lower part: it will make west winds for them, and here a morning wind arises from the air that follows it. This is also why, if it happens to catch up with another wind, the wind grows greater as it rises, because it has added to itself.
11| Why do dogs find scent trails least of all when the west wind is blowing? Is it because this wind confuses them most, being the most continuous of the winds and blowing especially close along the ground? Why, when stars shoot across the sky, is this a sign of wind? Is it because they are carried along by the wind, and the wind arises there before it reaches us? This is also why, from whatever region the stars are seen moving, the wind arises from that same region. Why does the west wind bring the largest clouds of all the winds? Is it because it blows from the open sea and along the sea's whole length? So it gathers clouds from a great expanse. Why are the winds greatest at their ending? Is it because, when they blow out all at once, little of the hot element remains?
12| Why, if the southwest wind blows around the equinox, does rain result? Is it because, in whatever region of the universe the sun is, it sets the winds from that region in motion? This is also why the shifting of the winds follows the sun's course. And since the equinox is the boundary between winter and summer, whenever it happens that the sun, at what appears to us as the equinox, has actually passed beyond, or has not yet reached, the precise boundary, and is more on the wintry side, it follows that the winds from that quarter blow, the first of which is the southwest wind, which is by nature moist. And when the sun is more in the wintry part of the universe, and sets the winds in it in motion, the effects of winter result; and rain is one of these. Further, since the equinox is, as it were, an even balance between winter and summer, if anything at all is added to either side, it makes the tilt clearly noticeable, just as with scales that are in balance. Since, then, the southwest wind belongs to the wintry rank and is by nature moist, its addition at the equinox produces a tilt toward winter, and rain; for rain is the weather-effect most proper to that wind.
13| Why are the south wind and the southeast wind, though hotter than their opposites — the north wind and the west wind respectively — more rain-bringing? And yet it is through cold that water is produced from air. For it is not because the north wind pushes clouds away from there that clouds form here; for the west wind and the southeast wind both drive clouds away in the same way (since they are alike oblique to the sun's path), and so do all the other winds, from wherever they blow. Is it because the cold gathers back inward more, when the heat is more outward? Or is it partly also because of the region from which they blow, that those winds are clear? For indeed the southeast wind comes from the dawn quarter, and this country lies toward the west, as does the west wind. But it is also because the air, having been heated first, like water too, cools most quickly and most completely. So the air from the southeast wind travels from the east while hot, and that from the south wind travels from midday. So when they arrive at a colder region they quickly freeze and condense into water. And the southeast wind produces rain more, because it carries the air more directly from the sun, and the air is correspondingly hot. And the south wind is rain-bringing at its ending, because the air first carried from the sea is cold, while the last of it, being thoroughly heated, is brought from the land. Or is this not the only cause, but also that the south wind grows greater as it ends? This is also why the proverb applies to it at its beginning too. And greater winds are colder; so they freeze the clouds later. Or is it for this reason that it is more rain-bringing at its beginning?
14| Why do winds dry things out, though they are cold? Is it because the colder winds cause evaporation? But why more than the sun does? Is it because they carry the vapor away, while the sun leaves it behind? So the sun moistens more but dries less. Why does the northeast wind alone, of all the winds, draw the clouds toward itself, as the proverb also says, drawing a cloud to itself like the northeast wind? For the other winds, wherever they blow from, push clouds back there instead. Is the cause that the opposite wind is blowing at the same time? But this would not have gone unnoticed; rather, wind naturally travels along the line of a circle. So the other winds blow around the earth, but the concave side of this wind's circle faces toward the heavens and not toward the earth, so that, blowing toward its own point of origin, it draws the clouds to itself.
15| Why doesn't a cold breeze blow off the sea at dawn, while one does off rivers? Is it because the sea lies in open regions, while rivers lie in narrow ones? So the breeze from the sea scatters over a large area, so that it is weak, while the breeze from rivers travels as a mass and is stronger; that is why it more plausibly appears cold. Or is this not the cause, but rather that rivers are cold, while the sea is neither hot nor cold? A breeze, an exhalation, arises from things being heated or being cooled: whichever of these a thing undergoes, it is turned into vapor, and when the water is turned into vapor, the air that results is carried along, and this is the breeze. So what comes off cold things plausibly blows cold, while what comes off very hot things cools as it blows and becomes cold. Now one would find that rivers are all cold, while the sea is neither very cold nor very hot. So what blows off it is not cold, because the sea is not very cold, nor does it cool quickly, because the sea is not very hot.
16| Why does the west wind seem to be the mildest and most pleasant of the winds, as indeed Homer says of it in the Elysian plain, "but always the breezes of the west wind blow through it"? Is it, first, because it has a blend of air? For it is neither hot, like the winds from the south and the east, nor cold, like the wind from the north, but stands midway between the cold and hot winds; and bordering on both, it shares in the power of each, and that is why it is well-tempered and blows especially in spring. Further, winds shift around either to their opposites or to the right. So, blowing after the north wind (since that quarter is on the right), it is well thought of, the way a mild thing is welcomed after a harsh one. And at the same time, when winter has run its course, fair weather tends for the most part to follow. And the north wind is a wintry wind. [And the east wind, since it lies midway between the hot and cold winds, shares less in them. For the east wind, in blowing, sets in motion the winds from the south (since that is the direction of its shift), but in moving them it does not mix with them. The west wind, by contrast, is itself set in motion by the south winds, and in blowing sets in motion the north winds; for it is here that the cycle of the winds comes to an end. That is why, having in itself the end of some winds and the beginning of others, it is rightly pleasant, and is thought to be so.]
17| Why does the south wind blow at the rising of the Dog Star? Is it because it gives a sign at the setting or rising of all the stars, and not least at this one? Clearly winds arise especially at this time and after it. And since the season is stifling, the winds set in motion at it are naturally the hottest; and the south wind is hot. And since—a period of time. Why does the west wind blow toward evening, but not in the morning? Is the sun, in rising and setting, the cause, for the most part, of the winds? For when it heats the air, which is moist, and concocts it and separates it out, it separates it into wind; and if the air is already windy, it is turned into wind still more by the sun. Now when the sun is at its rising, it is far from the region of the west wind, since that blows from the setting; but when the sun is already near its setting, then the wind has been completely separated out. And from midday toward evening the conditions are most proportionate for heating and separating it out. For these same reasons the east wind too begins to blow in the morning: since the air above the earth has been made moist during the night and, because of its weight, has settled close to the earth, the sun at dawn, in separating this air out, first sets in motion the air in its own region. And the wind that comes from the direction of the rising sun is for this reason called the east wind.
18| Why, as the sun rises, do the winds both increase and fall off? Is it because wind is a motion either of the air or of moisture that has been drawn up? When this moisture is small in amount, it is quickly used up by the sun, so that no wind arises; but when it is greater, it is set in motion more once the sun has risen, since the sun is a principle of motions. Why does the west wind blow toward evening? Is it that all winds arise from the sun dispersing moisture? For what was previously condensed, when the power of heat draws near, it kindles into wind. Now the west wind blows from the west. It reasonably arises toward evening, then, since that is when the sun reaches its region. And the north and south winds blow most often for this reason: that a thing overpowered by its opposite is least able to persist against it in a straight line, but rather from the side. So the south and north winds blow from the regions on either side of the sun's course, while the other winds blow more from directly opposite it.
19| Does wind travel from some source, as water does, such that it cannot be carried higher than that source, or not? And does it come from a single point, or from a more extended region? There are some respects in which winds resemble what is observed to happen with waters as well: water, when it is carried down a slope, flows faster than when it lies stagnant on a level, even surface. Winds are similar: on peaks and heights the air is always in motion, while in hollows it often lies still and there is no wind at all. Further, on very high mountains winds do not occur, as on Athos and other mountains of that kind. Here is a sign: whatever offerings those sacrificing in the previous year leave behind, they say are found still there, undisturbed, the following year. It is clear, then, that the movement of wind, like that of water, comes from some source. So it can no longer make its way upward beyond that source. This, then, is why this happens on high places. The same would hold for water as well: for neither a raging torrent of water nor an extraordinary wind is observed to occur on high places.
20| Why is it that when the south wind blows the sea turns deep blue, but when the north wind blows it turns dark? Is it because the north wind disturbs the sea less, and everything less disturbed appears dark? Why do south winds, when they blow lightly, not produce cloud-cover [or massing of cloud], but when they become strong they do produce cloud-cover? Is it because when blowing lightly they are not able to make many clouds? So they hold sway over only a small region. But when they become strong, they drive along many clouds, and that is why they are thought to bring on cloud more. Why is the north wind strong at its onset but weak as it dies down, while the south wind is weak at its onset but strong as it dies down? Is it because the north wind is near us, while the south wind is far off? The north wind, then, as soon as it begins, is immediately upon us, while the beginning of the south wind, since it has a long distance to travel, gets dispersed, and only a small part of its first onset reaches us; and of its ending, we perceive the one wind's but not at all the other's. So it is reasonable that the one dies down weak (since the ending of everything is weak), while the other does not seem to: for we no longer perceive its ending at all. Why is it that where there are gulfs, backing winds occur, but where there are open seas, they do not? Is it because a wind flowing into gulfs is not so much scattered, but is carried along mostly as a mass, whereas in open waters, from the start, the land-breezes are immediately more scattered, and when they do flow, they undergo the same thing, because there is room to rush off in many directions? For a backing wind is a bending-back of a land-breeze.
21| Why is it said, "at the beginning of the south wind and the ending of the north wind"? Is it because the north wind, since we dwell close under it and our habitation lies toward the north, blows strongly at once? For it is present as soon as it begins. Hence it blows pleasantly as it dies down, since then it blows weakly. But the south wind, because it comes from far off, arrives greater later. Why do people feel heavier and more feeble in south winds? Is it because a great deal of moisture arises from a little, being melted by the warmth, and moist air, though light, becomes heavy? Then their strength grows slack. Why are people hungrier in north winds than in south winds? Is it because the north winds are colder? Why does the south wind not blow along Egypt itself near the sea, not even for as much as a day and a night's journey, while above Memphis, at a distance of a day and a night's journey, it blows strongly; and toward the west it does not blow for about two days and nights' journey, while toward the east the southwest winds blow? Is it because Egypt is hollow in its lower parts? Hence the wind passes over it, while the regions further up and further off are higher.
22| Why is the south wind small at its beginning but grows greater as it dies down, while the north wind does the opposite—hence the proverb that it is well to sail at the beginning of the south wind and the ending of the north wind? Is it because we dwell more toward the north than toward the south, and the north wind blows from the north, the south wind from the south? It is reasonable, then, that the north wind, being violent from the start, presses more upon the nearby regions, and afterward its violence shifts toward those farther off. The south wind, on the contrary, presses at its beginning upon those who dwell toward the south, but when it has passed by, it blows strongly upon those toward the north. Why is it said, "if the south wind summons the north wind, a storm comes at once"? Is it because the south wind is of such a kind as to gather clouds and much water together? So whenever, this condition prevailing, the north wind blows in addition, since much matter is available to it, it congeals it and makes a storm. Hence it is said, "if the north wind seizes upon mud, a storm comes at once." For mud, and water in general, arises from the south wind either most of all or most often. Why does the north wind fall quickly upon the south wind, but the south wind does not fall quickly upon the north wind? Is it because for the one the arrival is from nearby, but for the other from far off? For our habitation is toward the north.
23| Why are winds cold, though they arise from a stirring caused by what is hot? Is it not the case that motion caused by heat is not in every way hot, unless it comes about in a certain manner? Rather, if it falls all at once, the very thing that releases the heat burns. But if it comes through a narrow passage and little by little, the motion itself is hot, but the air moved by it, being whatever it happened to be beforehand, produces a motion of that same kind—just as with the body. For people say that we breathe out hot and cold from the same source, but this is not true; rather, what goes out is always hot. A sign of this is that if you bring your hand close, it appears so. But its manner of release differs. For if we breathe it out with mouth wide open, through a large opening, it appears hot because we perceive the breath itself; but if through a narrow opening, becoming more forceful, it pushes the neighboring air, and that pushes the air next to it in turn. Since that air is cold, its motion too becomes cold. Perhaps the same thing happens in the case of winds as well: the first motion is through a narrow passage; then that air moves on, and other air flows in besides. This is why winds are hot in summer but cold in winter, because in each case the pre-existing air is of that kind. Since it is clear that the air is not carried in this direction either by being moved of itself or by being mastered by the heat—clear not only from this, but also because, if the heat present in greater amount warmed the winds, it would be carried upward. For that is the nature of fire, while what is cold is naturally carried downward. But winds move sideways, reasonably so; for since the one force drives them upward and the other downward, and neither prevails, and they cannot remain still, it is reasonable that their motion becomes oblique.
24| Why are south winds cold in Libya, just as north winds are among us? Is it, first, because in the one case the origins of the winds are nearer to us, and in the other nearer to them? For if, as we said, winds arise through a narrow passage, they will be colder for those nearer to their source, on account of the intensity of the motion; for as it proceeds further off, it disperses. Hence among us too the north winds are cold, because we are nearer to them and dwell altogether close to the north. Why are dry south winds, those not accompanied by rain, feverish? Is it because they produce in bodies a foreign hot moisture? For they are moist and hot by nature, and this is what is feverish; for fever arises from an excess of both of these together. So whenever they blow under the sun's influence without rain, they hold this character; but whenever they blow together with rain, the rain cools them down. Why do the etesian winds always blow at the same season and in the same numbers? And why do they die down as the day ends, and not blow during the night? Is this because the melting snow stops being melted by the sun toward evening and during the night? And in general they blow when the sun begins to prevail over and dissolve the ice toward the north. So at the beginning of this the forerunner winds blow, but once it is already being dissolved, the etesian winds blow.
25| Why is the west wind the smoothest of the winds, and cold, and blows especially in two seasons, spring and autumn, and toward evening of the day, and especially over land? Is it cold because it blows from the sea and from open plains? It is less cold than the north wind because it blows from water turned into wind rather than from snow; but it is cold because it blows after winter, when the sun has only just begun to prevail, and in autumn, when the sun no longer prevails—for it does not, as on land, linger to hold the heat, but wanders because it travels over moisture. And it is uniform for the same reason; for it does not blow from mountains, nor from something melting by force, but flows easily as if through a channel. For the regions toward the north and south are mountainous, but toward the west there is neither mountain nor land, only the Atlantic sea, so that it is carried over the sea. And it blows toward evening of the day because of its location; for then the sun draws near to that region. And it stops during the night because the sun's motion then ceases. Why, when the east wind blows, do all things appear larger—is it because it makes the air most murky?
26| Why do the winds blow early, from the dawn, in winter, but in the evening, from the west, in summer? Or is it that what happens to us in summer happens in winter to those who inhabit the opposite hemisphere of the earth, while for us in winter the winds blow early and from the dawn because the air, being thoroughly moist during the night, is separated out and set in motion in the morning by the sun—first the air nearest to the sun? The sun does this even before sunrise; that is why breezes blow no less before sunrise. Since, then, the sun draws moisture to itself and, before sunrise in winter, sets in motion the air near us, which is moist, it is clear that it would likewise draw moisture to itself when it is in the lower hemisphere, and evening for them is what dawn is for us. So it would follow that the air drawn to itself by the sun before sunrise from us becomes, for those below, a west wind, and blows in the evening. And what happens to us in our winter corresponds, for them, to their dawn; and what happens in our summer corresponds, for us, to evening. For when it is summer with us, it is winter there, and our evening is their dawn. At that time breezes happen to blow from the east for them, but west winds for us, for the same reasons as stated. In summer, east winds do not blow at dawn, because the sun rises upon air that is still drier with us, since only a little time has passed since it set; and west winds do not blow in the evening in winter, because in the lower hemisphere there are no east winds at that hour either, for the reasons stated—so that it is the sun drawing the moisture to itself that produces our west wind.
27| Why does the west wind seem to be the mildest and most pleasant of the winds? Is it because it lies on the border between the hot and the cold winds, and, being neighbor to both, shares in the power of each? That is why it is well-tempered. The east wind shares in this less, though it too lies in the middle of the same winds; for when the east wind blows it sets the winds toward the south in motion (for that is the direction of its shift), but in setting them in motion it does not mix with them. The west wind, however, is itself set in motion by the south winds, and in blowing it sets the north winds in motion; for the cycle of the winds ends there. Since, then, it has in itself the end of the one set and the beginning of the other, it is with good reason pleasant, and is thought to be so.
28| Why are different winds rain-bringing in different places—for instance in Attica and the islands the Hellespontian, in the Hellespont the north wind, and likewise in Cyrene, but around Lesbos the south wind? Is it that wherever there is a gathering of clouds, there is rain? For it is there that the condensation collects, wherever it has somewhere to settle. That is why it rains more in the mountains than where the mass of cloud can pass on through; for when hemmed in it is condensed, and this must happen. And it rains more in calm weather. In the Hellespont, then, the north wind drives together many clouds from above, but toward Attica and the islands the Hellespontian wind does so, having them as it were as material; for most clouds gather round from the north wind. Around Lesbos the southeast and south winds, bringing many clouds from the open sea, drive them against the land. The same holds in the other cases too. Why is it said: never fear a cloud from the mainland, but from the sea, in winter; in summer, though, from the black mainland? Is it because in winter the sea is warmer, so that if anything has formed there, it clearly has formed from a strong source—for it would have been dissolved, since the place is warm? In summer, on the other hand, the sea is cold, and so are the winds off the sea, while the land is warm, so that if anything is carried from the land, it has formed from a greater source—for it would have been dissolved, had it been weak.
29| Why is it that in Arcadia, though it is high country, the winds are no colder than elsewhere, but when there is no wind and the sky is overcast it is cold, as in flat marshy regions? Is it because Arcadia too becomes like marshy country—for it has no outlets for its waters to the sea, and that is why there are many chasms there? So whenever there is wind, it fans away the exhalation from the earth, which is cold, while the winds themselves are not cold, because they strike in from the sea; but in calm weather the vapor rising from the standing water produces the cold. Why is it that, if the wind begins to blow at dawn, it tends to blow all day long? Is it because the motion is most vigorous when the sun is just beginning, and so, being of this kind, it extends further? A sign of this is that the formation is strong. Why is the north wind bright by day but drops at night? Is it because it arises from frozen rain, whenever this is drawn up as vapor by the sun's action? It drops at night because the process of generation is not the same, but works in the opposite way; for it breathes out at night, and less by day.
30| Why, when spider-webs are carried about in quantity, are they a sign of wind? Is it because the spider works in calm weather, and the webs are carried because the air, being chilled, contracts toward the earth, and chilling is the beginning of winter—so the carrying of the webs is a sign? Or is it that after rains and storms the mass-carrying of webs occurs, because the spiders have been working during the calm weather, since they are not seen working in winter, this being a thing they cannot bear the cold for; and being carried by the wind, they get unspooled a great deal. And after rains, winds generally tend to arise. Why are strong north winds in winter cloudy in cold regions, but clear outside them? Is it because they are at once cold and strong, and colder the nearer they are, so that they freeze the clouds before they can drive them off; and once frozen, the clouds remain, because of their weight? Farther out, the north winds work more by their strength than by their cold.