BİRİNCİ FEN · ÜÇÜNCÜ BÂB · ÜÇÜNCÜ FASIL · Birinci Madde
Article One
Concerning certain conditions of the lowest stratum of the element of air.
O esteemed one! Know that philosophers and astronomers are agreed upon the following: The lowest stratum of the element of air is the fourth stratum relative to the fiery stratum, and its air is in motion with various movements. Its thickness and depth extend approximately more than sixteen farsakhs.
This lower stratum is a layer of air so dense that it is proximate to the earth and water, such that the rays of sunlight and the reflections of stars falling upon them are moderated [tempered]. The cold breezes coming from the seas are transformed within this air stratum and lose their effect.
Rainbows, halos, smoke, frost ( *jâle*), dawn, twilight, night, day, and winds; all these occur within this stratum. Were it not for this stratum being temperate as mentioned above, its coldness, derived from the earth and water, would be more intense than that of the wintery stratum. As is the case in polar regions where the sun is distant from the zenith, the air becomes so intensely cold that seas freeze, and no place remains uncovered by snow (and ice). Due to this severe cold, plants and animals perish there (except for those adapted to the region). The cultivation of that region is impossible.
The sphere of air is divided into three strata: the highest being close to the fiery sphere and exceedingly hot; the middle stratum, due to its proximity to rising vapors of water, is excessively cold; and the lowest stratum is adjacent to earth and water; but it has become temperate through the reflection of rays. Therefore, it is called the sphere of winds (*kure-i nesîm*). Because it is mixed with vapor and smoke, it is also called the sphere of vapor and the sphere of smoke. The air in this stratum is dense, so that sunlight only becomes apparent when it reaches this stratum, and the shadow of the earth is observed and rotates within it. Therefore, it is also called the sphere of night or the sphere of day. It is due to the color [quality] of this sphere that the sky appears blue. For according to most philosophers, there is no day or night above this stratum. The lights of the sun and other stars do not appear in subtle bodies – apart from the dense body of the lunar sphere – but are reflected within them. But those other stars are like a pure light, “which is neither attributable to the west nor to the east.” (See en-Nur 24:35) There is neither morning nor evening there. "Allah guides whom He wills with His light." (Nūr, 24:35)
The height of this stratum from the earth’s surface is as described in its thickness, which has been calculated to be more than sixteen farsakhs.