97. Allah (swt) chose a specific word here “yuzji” with its root in “zaja” which is used in the Qur’an in reference to clouds alone. Lisan and Sihah say it is for pushing forward a thing gently. The connotation fits well the cloud formation described below (Au.).
98. It is commonly stated in science books and unquestionably accepted by the readers that the winds drive the clouds. In a sense this is true. But it is forgotten that the winds normally have the scattering effect and do not collect together to close gaps in gas particles. We have to understand the Qur’anic statement then, as alluding to the role the winds play in condensation of water particles (Au.).
99. The textual word “rukaam” gives the sense of something piled one upon another: an accurate description of the formation of rain clouds in the atmosphere (Au.).
100. The word “wadq” has two meanings: rain as well as lightning (Qurtubi). The word was chosen perhaps to express both the meanings, and which fits the context (Au.).
101. The word in the original for “midst” is “khilaal” which is the plural of “khalal.” It should be strictly translated as “interstices” – as done by Majid – which in turn is explained by the dictionaries as “a small or narrow space or interval between things or parts, esp. one of a series of alternating uniform spaces and parts: e.g., the interstices between the slats of a fence. The word seems to fit wonderfully with the process of rain drops leaving the saws in the final stages of rain formation. We might in a few lines try to understand cloud formation and rains – otherwise an extremely complicated process, a miracle by itself –in the following, taken from several scientific works:
Most people do not know that cloud formation is a miraculous event. Thousands of things have to happen for the clouds to form: and they must happen at the right time and right place, at right temperature. In fact, the process is so complicated, that no prediction can be made of when and where clouds will form. Nevertheless, since rain patterns are surprisingly regular, as against the expected haphazard pattern, it can be concluded that an external Agency is in control of the process. Herewith a short, brief, and therefore an incomplete account to impress on the reader that if not for Allah’s power, vapors rising from the earth could not coalesce into clouds to ultimately fall back as rain, consistently falling in the same place – year after year, following a certain pattern.
Clouds are formed by the lifting of damp air which cools by expansion under continuously falling pressure. The relative humidity increases until the air approaches saturation. Then condensation occurs on some of the wide variety of aerosol particles present. For continued condensation leading to the formation of cloud droplets, the air must be slightly supersaturated. Among the highly efficient condensation nuclei are the salt particles produced by the evaporation of sea spray, but it appears that particles produced by human-made fires and by natural combustion (for example, forest fires) also make a major contribution. Condensation onto the nuclei continues as rapidly as the water vapor is made available by cooling of the air and gives rise to droplets of the order of 0.01 mm in diameter. These droplets, usually present in concentrations of several thousand per cubic inch, constitute a non-precipitating water cloud.
Growing clouds are sustained by upward air currents. Considerable growth of the cloud droplets is necessary if they are to fall through the cloud, survive evaporation in the unsaturated air beneath, and reach the ground as drizzle or rain. Drizzle drops have radii exceeding 0.1 mm, while the largest raindrops are about 0.24 in. (6 mm) across and fall at nearly 10 m/s.
Cloud droplets are seldom of uniform size for several reasons. Droplets arise on nuclei of various sizes and grow under slightly different conditions of temperature and supersaturation in different parts of the cloud. Some small drops may remain inside the cloud for longer than others before being carried into the drier air outside.
A droplet appreciably larger than average will (within the cloud) fall faster than the smaller ones, and so will collide and fuse together) with some of those which it overtakes.
The second method of releasing precipitation can operate only if the cloud top reaches elevations where temperatures are below 32°F (0°C) and the droplets in the upper cloud regions become super-cooled.
In a cloud composed wholly of liquid water, raindrops may grow by coalescence with small droplets. For example, a droplet being carried up from the cloud base would grow as it ascends by sweeping up smaller droplets. When it becomes too heavy to be supported by the vertical upcurrents, the droplet will then fall, continuing to grow by the same process on its downward journey. Finally, if the cloud is sufficiently deep, the droplet will emerge from its base as a raindrop.
In a dense, vigorous cloud several kilometers deep, the drop may attain its limiting stable diameter (about 0.2 in. or 5 mm) before reaching the cloud base and thus will break up into several large fragments. Each of these may continue to grow and attain breakup size. The number of raindrops may increase so rapidly in this manner that after a few minutes the accumulated mass of water can no longer be supported by the upper currents and falls out as a heavy shower. The conditions which favor this rapid multiplication of raindrops occur more readily in tropical regions.
(To be Continued)