BİRİNCİ FEN · ÜÇÜNCÜ BÂB · ÜÇÜNCÜ FASIL · Dördüncü Madde
**Article Four**
Concerning the natural changes occurring in the air surrounding us.
Esteemed one! Know that the philosophers have stated: Surely, within the air surrounding us, there occur natural and unnatural alterations, and sometimes transformations contrary to the natural courses.
As for the natural changes, these are primarily those arising in relation to the seasons. For [66/a] each season undergoes a change (in the air) and assumes a different temperament. For example, in springtime its temperament is moderate, in summer it is hot, in autumn it approaches moderation, and in winter it is exceedingly cold.
Although, according to physicians, the temperament of these four seasons and their days vary according to regions and climates [just as winter is not equally severe in every region, nor are the transitions between two springs consistently moderate in every climate]. The astrologers, however, do not give credence to these regional variations.
For they say that the occurrence of the four seasons takes place as follows: – the movement of the great luminous sun towards the west, reaching a quarter of the zodiacal wheel (the point of equinox) is springtime. This corresponds to its being in the signs Aries, Taurus, and Gemini. When it is in Cancer, Leo, and Virgo, it is summertime. When it is in Libra, Scorpio, and Sagittarius, it is autumn. And when it is in Capricorn, Aquarius, and Pisces, it is wintertime.
As for the difference between the four seasons, this is entirely dependent on the proximity of the great luminous sun to its zenith point and its distance from its ascending node.
Thus, the heat of summertime arises from the sun’s proximity to its ascending node and the strength of its rays. For in summertime, these rays do not fall upon the regions at narrow or perpendicular angles, but all fall with wide angles; or they return on the points where they fall with the same angles. In this way, the rays are very intense, and their heat is doubled, thereby making the air surrounding us exceedingly hot.
The primary reason for this is that some of the places upon which the sun’s rays fall become cylindrical and conical (in a manner that obstructs the return of the ray). As if the sun's rays emanated from its center and penetrated into the interior of an object facing it. Some of the places from which the rays originate are simply enclosed or nearly enclosed. However, the effect of the strength of the rays is within the "partes" (quarter). [519] For its influence is suitable for direction in all ways. Its influence on nearby locations is weak. For we find ourselves in the northern hemisphere (according to the angles at which sunlight falls upon the earth). Therefore, during summertime, we are located in a geography where the sun’s rays are either on or near their meridian.
In wintertime, however, we are located either around or near the circumference of the places where the sun's rays fall. That is why, in summertime, even though the course of the sun rises above its orbit and is distant from the earth, its light comes strongly to our region, and its heat is effective. In wintertime, however, although the mass of the sun is drawn back within its orbit and is close to the earth, its light comes weakly to our region, and the temperament of the air is exceedingly cold. In summertime, the solar disk is very near our ascending node point. In wintertime, it is quite distant from our ascending node point. But in springtime and autumn, the angles at which the sun’s rays fall are midway between the aforementioned circumferences, so that warmth and coolness are moderately temperate. As will be explained below.