BİRİNCİ FEN · ÜÇÜNCÜ BÂB · İKİNCİ FASIL · Üçüncü Madde
Third Article
Concerning the measurement, characteristics, and movements of the middle layer of the aerial sphere, and what occurs within it.
Know, esteemed one! Philosophers and astronomers have stated: The middle layer of the aerial sphere is the third in relation to the fiery layer, and it remains stationary within its own domain. Its thickness and depth are approximately five thousand ten (5010) parasangs. Because the heat of the element of fire does not descend into this layer, nor does the warmth of the sun’s reflected rays ascend here, this aerial layer is mixed with water vapor, and due to this influence, it is exceedingly cold. For this reason, it has become renowned as the “zemheri layer.” It is known as the source of clouds, rain, and snow.
Furthermore, hail, thunder, and lightning also occur within this layer and descend below. The cause of most of these precipitations (the aforementioned types) is small droplets of water that are thinned by the heat of reflected sunlight and separate from one another with the aid of air particles.
Then, these transparent vapor droplets become so intertwined with air particles that they cannot be separated, ascend into the heavens, and the vaporous particles enter a process of re-condensation. For the luminous Sun radiates light upon the seas and lands, and through the heat generated by its reflections, the watery portion evaporates and gradually emerges, mixing with air particles and evaporating. Simultaneously, subtle bodies hidden within the earth are revealed and mix with the air as they evaporate. As these vapors ascend into the upper layer of the aerial sphere, they rise to the cold layer.
For masses of vapor and smoke are drawn toward that layer. Thus, the aerial layer combines due to the influence of these two mixtures and begins to move in various directions. The effect of cold from above, along with the influence and pressure of the vaporous and smoky layers below, cause all of these things to intermingle—resembling a kind of conflict. During these comings and goings, a certain condensation occurs due to the influence of the cold.
If the cold is not severe, clouds form from the vapors that mix and gather together, and the higher this cloud rises, the more the vapor particles intertwine, the fumes turn into air, and wind results. When the vapor particles begin to transform into water and unite with one another, a certain degree of condensation occurs, and as a result of this condensation, they become raindrops and begin to fall towards the earth. If the ascent of the vapor has occurred at night and at that time the coldness of the air is also severe and strong, reaching the clouds before they have had time to coalesce, then it becomes snow and gently descends upon the earth. If, however, the cold is exceedingly intense when the vapor particles meet each other after uniting within the cloud, hail forms and begins to fall rapidly, striking the ground.
And if the heat of the rising vapor is less than the coldness of the air and does not reach the aforementioned cold layer above, and its quantity is abundant, it either becomes a rain cloud or a white cloud that appears like heaps of cotton tossed in the spring—piling up like mountains and forming strange shapes and bizarre forms. These layers are so subtle that they mix with the air due to their lightness over time. If the mass of vapor rising with little heat is itself small, its condition should be explained in the lower layer where it belongs. For sometimes intense cold causes a contraction and closure in the air, clouds form within the zemheri layer, and from them rain, snow, and hail emerge.