BİRİNCİ FEN · ÜÇÜNCÜ BÂB · ÜÇÜNCÜ FASIL · Altıncı Madde
Sixth Point
It describes the changes occurring in the air surrounding us—due to non-natural causes originating from the earth—such as the differences in height and depth of the lands, resulting in variations in mountains, seas, winds, and soil.
Beloved! Know that philosophers have said: It is certain that changes will occur in the air when a region is found at a high or low elevation. The air in a place located at altitude is always cold. The air in a low-lying place, however, is constantly hot (and dense). For the heat acquired by the earth’s rays during their reflection from the ground is intense and concentrated on the areas close to the surface; thus, the part of the surrounding air mass closest to the earth is its hottest portion. And as the air moves away from the earth, it approaches a colder layer and cools along with its surroundings. If the aforementioned low-lying place is a deep valley, then by virtue of its structure, it retains the warmth of the sun’s rays. Therefore, its air is hot and dense.
The cause of changes in the air due to mountains is clear. For if a settlement is built on a mountain—as mentioned above—its air will be colder than that of plains. If the mountain is near the settlement, it has been observed through experience that the mountain’s mass of air affects the area in two ways: First, it either reflects sunlight onto the settlement or acts as a screen, blocking the rays and diverting them elsewhere [67/a]. The second effect relates to the wind; it either acts as a barrier, preventing the region from receiving wind, or directs breezes towards it, increasing their intensity. An example of the first effect is when the mountain is located near the north of the region. In that case, it spreads sunlight upon the mountain and allows the rays to strike the area. No matter how high its latitude, it warms the air surrounding the region. And if the mountain is located west of the region with an open eastern side, then the sun’s effect still heats the region's air.
If the mountain is located east of the region with an open western side, then the sun heats the air only halfway, for the sun's rays do not affect it until after its zenith and as hours pass, the mountain moves away from the sun, reducing the impact of sunlight and preventing complete warming of the air. However, as the sun moves towards the west of the mountain, it draws closer to it each hour (until full reflection occurs), completely heating the region's air. And if the mountain is located near the south of the region, then it cannot heat the region’s air at all.
The mountain’s second-order effect is that it prevents cold northern winds from blowing across the region. This either lifts warm southern winds out of the area or—if the region lies high between two large mountains and is open to the wind's direction—allows the wind to blow with greater intensity than it would over a flat plain. For when wind is directed into a narrow space, its current does not stop; it rushes like a stream, finding no tranquility. In terms of relationship with mountains, the most temperate regions are those whose eastern and northern sides are open while their western and southern sides are sheltered by mountains.
Regarding changes in the air due to seas: The climates of all regions surrounding a sea are humid. If the sea is located near the north of a region and northern winds blow over it, then that wind will affect the region’s air to make it exceedingly cold, for water itself possesses a nature like that of northern winds—coldness. If the sea is located near the south side of the region, it exerts an excessive weight on the region's air. However, if there is also a mountain to the north, preventing wind from passing through, then the region’s air becomes very heavy and dense. If the sea is located east of the region, it affects the region’s air to be excessively humid, for abundant sunlight approaches that area. And if the sea is located west of a region, its contribution to the region's humidity will be minimal, for the sun seems to merely graze and quickly depart from that place. The winds corresponding to this meaning are the north, east, and west winds; while the south wind is harmful.
Changes in the air due to winds have been experienced as follows: Northern winds are cold and dry. Their coldness stems from the wind passing over cold mountains before reaching us. Their dryness arises from the weak incidence of sunlight on that region, resulting in minimal evaporation. As for eastern winds, they are moderate in terms of heat and cold; however, they tend to be dry because they pass through mountains and arid climates. Western winds are also moderate but often humid because they come from the seas. Southern winds, however, are generally hot and humid in many regions, due to their origin from areas that have been heated by proximity to the sun. Their humidity arises from the fact that the seas in southern regions dissolve under the influence of the sun’s heat, and this warmth causes the sea water to evaporate and mix with the winds. This is why southern winds are debilitating to the body. The *sam*, or [67/b] destructive winds, as explained above, are those that reach us having passed through excessively hot regions.
The smoke is a wind carrying heavy layers of soot, descending and mixing with the earth; whatever living thing it encounters at that hour, it consumes and turns to black ash, destroying it utterly. Winds of the heavens alter all the aforementioned rules and transform them into something else. All violent winds begin as gentle breezes from the lower strata, yet their origin, essence, and intensity are from above.
As for changes in air caused by the earth, they vary according to regions. The reason for this difference is that some regions have clayey soil, others stony (barren), still others sandy, some black humus, and some places rich in minerals. Thus, all these types of soil not only alter the nature of water found within them but also influence changes in the air's nature. With Allah’s permission, they effect such changes. For in this universe, from molecule to galaxy, everything emerges into existence, completes its duration, and then is withdrawn. All that they do is within Allah’s knowledge, by His will, and through His power. There is no doubt about it. The Powerful and Ever-Living is only Allah; His glory is exalted.