The influence of changes in the air, not too contrary to the natural course of things

Now we should supplement our reasoning by mentioning other unusual changes in the air, which are not contrary to nature and occur depending on heavenly and earthly circumstances. We have already pointed out many of them when talking about the seasons. As for changes that are subject to celestial circumstances, this is, for example, what happens due to the celestial bodies. The fact is that sometimes many bright stars gather in one area of ​​​​the sky and they meet the sun, this causes a lot of heating in the place over which they are located or close to it. And sometimes they move a considerable distance away from the zenith and the heating turns out to be insufficient. The very fact that the sun is at its zenith does not have the same effect on heating as the duration of the sun's stay above people's heads or close to the zenith.

As for earthly circumstances, some of them are determined by the latitudes of certain countries, others by the elevated or lowland position of the area, some by mountains, some by seas, some by winds, some by soil.

As for the circumstances due to latitude, any area close to the Tropic of Cancer in the north and the Tropic of Capricorn in the south experiences hotter summers than areas further towards the equator and north. The words of those who believe that the areas lying under the equator are close to balance should be considered correct. The fact is that there is only one heavenly warming factor here - the sun being at its zenith. However, the presence of the sun at its zenith does not in itself have a significant effect; Only the duration of the sun's stay above the head has an effect. That is why the heat after the middle prayer is stronger than the heat at noon, and for the same reason the heat at the end of the month of Saratan and at the beginning of the month of Asad is stronger than when the sun has reached its maximum declination. As a result of this, the sun, when it has moved away from the Tropic of Cancer to some part of the zodiac located below the declination, warms more strongly than when it is in the same area according to the degree of declination, but has not yet reached the Tropic of Cancer. In areas adjacent to the equator, the sun remains at its zenith for several days, then moves away with great speed, because at the equinox points the increase in degrees of declination relative to each other is much greater than at the solstice points; sometimes even the movement of the sun at the solstice points for three, four or more days does not make a tangible impression. Further, the sun remains there for a long time in one part of the sky, close to people, and warms more and more. Based on this, it should be assumed that countries whose latitudes are close to full declination are the most

warm countries. Behind them come areas distant from the equator in both directions towards the poles, at a distance close to fifteen degrees. The heat at the equator is not as excessive as when the sun is at its zenith, near the Tropic of Cancer, in the inhabited part of the earth, but the cold in countries farther north from this tropic is greater. This is what is obligatory if we take into account the latitudes of the areas, although in other respects these areas are similar to each other.

As for the phenomena caused by the position of a particular area on a hill or in a lowland, the area located in the lowlands is always hotter, and the one that is elevated and located high is always colder. After all, that part of the air surrounding us that is closer to the earth is hotter, due to the increased heat of the sun's rays close to the earth, and that part that is distant from the earth to a certain limit is colder; the reason for this is stated in the natural history part of philosophy. When the lowland is like a depression, it compresses the rays of the sun even more and is therefore even hotter.

As for what is caused by mountains, the discussion about the mountain as a location is included in that part of the book that we have already outlined; now we want to talk about the mountain as a nearby hill. We will say: a mountain acts on the air in two directions: firstly, by the fact that it casts the rays of the sun onto the terrain or closes them in front of it, and, secondly, by the fact that it does not let in the wind or, on the contrary, helps it to blow .

As for the first point, if, for example, in some area, even in the north, there are mountains adjacent to this area from the north, then when the sun in its circular motion appears above these mountains, the heating of the mountains by the sun is reflected on the area and heats it up, even if the area lies in the north. The same thing happens if the mountains are on the west side, so that the east remains open; if the mountains are on the eastern side, this phenomenon is observed to a lesser extent. The fact is that when the sun sets and illuminates these mountains, it moves away from them every hour,  and the warming quality of the rays falling from the sun onto the mountain decreases, and when the mountains are located to the west, this is not the case, for the sun is with getting closer to them every hour.

With regard to holding back the wind, it must be said that the mountain either blocks the path of the cold wind from reaching the area, or enhances the blow of the hot southern wind, or, if the area is located between the steep slopes of two mountains and is open to the wind, then the wind blows there stronger than in flat terrain, since the air tends not to calm down if it is drawn into a narrow passage and the drawing continues for a long time. The same thing happens with water and other liquids, the reason for this is known in natural sciences. It is best for the terrain, in terms of mountain cover or lack of cover, for it to be open towards the east and north and covered on the west and south sides.

As for the seas, they cause an increase in humidity in all neighboring countries in general. If the sea is adjacent to the north, this helps to cool the area, as the north wind sweeps over the water, which is cold by nature. If the sea is adjacent to the south, this causes an increase in the compacting effect of the wind from the south, especially if it does not find a passage, since there is a mountain in this direction. If the sea lies in the direction of the east, then it humidifies the air more than if it is in the west, since the sun is constantly above the eastern sea and produces evaporation, which increases as the sun approaches, and the sun is not always above the western seas. In general, the proximity of the sea causes humidification of the air.

If there are many winds and they are carried away, not blocked by mountains, then the air is more protected from putrefaction; if the wind cannot blow freely, then it is prone to putrefaction and contributes to the decay of the juices. The most useful winds in this regard are the northern ones, then the eastern and western ones, and the most harmful are the southern winds.

As for air changes caused by winds, we can talk about this in two ways: speaking in general, of course, and speaking in connection with a particular country and its characteristics. Generally speaking, southern winds in most countries are hot and humid. They are hot because they come from areas heated by the proximity of the sun, and their humidity is explained by the fact that most of the seas are located to the south of us. Although these seas are southern, the sun acts on them with great force and produces vapors that are mixed with the wind. Therefore, southern winds become relaxing.

And the northern winds are cold, since they pass over mountains and cold areas where there is a lot of snow, and dry, because a little vapor is mixed with them due to the fact that evaporation is less in the north. In addition, they do not pass over flowing and sea waters, but in most cases pass over frozen waters or over deserts.

The eastern winds are balanced in terms of heat and cold, but they are drier than the western ones, for there is less steam in the northeast than in the northwest, and we, in any case, are inhabitants of the north.

Western winds are slightly wetter because they fly over seas and because the sun's movement is opposite to their movement. The sun and the western winds seem to oppose each other in movement, and the sun does not dry them out as much as it dries out the eastern winds, especially since eastern winds most often blow at the beginning of the day, and western winds most often blow at the end of the day. Therefore, western winds are less hot than eastern winds and more prone to cold, and eastern winds are hotter, although both eastern and western winds are balanced in comparison with southern and northern winds.

The influence of winds in different areas varies depending on other reasons. It happens that in some countries the southern winds turn out to be colder, since there are snowy mountains nearby, standing in the south, and the southern winds, passing over them, become cold. Sometimes northern winds are hotter than southern ones if they pass over hot deserts. As for simooms, these are either winds passing over very hot deserts, or winds of a kind of smoke that produce terrifying phenomena in the air, similar to fire. If such winds are heavy, then they happen to catch fire and ignite. Then the light air leaves them, and the heavy air falls down, retaining the remnants of ardor and fieryness. According to ancient scholars,  all strong winds begin at the top; although the source of their matter comes from below, the beginning of their movement, wind and breath extends from above. This judgment is either general or applies to most cases; finding out the truth of this is the task of physical science, which belongs to philosophy. In the section on housing we will devote a special paragraph to this. For now, this is enough.

As for the difference between localities in regard to soil, this difference is caused by the fact that the soil is sometimes clayey, sometimes rocky, sometimes sandy, sometimes silty, sometimes saline, and sometimes mineral strength predominates in the soil. All this has an effect on the air and water of the area.