Geoscience

Mountains in the Sky

5 min read · 907 words
Scientific Context
Mountains in the Sky

The Genesis of a Thunderstorm

The formation of a hail-producing thunderstorm is a sequence. It begins when warm, moist air rises. As the air ascends, it cools, and the water vapour it carries condenses into droplets. The condensation releases heat, which makes the surrounding air more buoyant, which drives the air higher still. A column of rising air, called an updraft, develops and can reach speeds of more than 80 kilometres per hour. As the column builds vertically, it can extend from near the ground to altitudes above 15 kilometres, growing through the entire depth of the troposphere. The system, now a cumulonimbus cloud, is mature.

The structure of a mature cumulonimbus is layered. Near the base, the air is warmer and the cloud is composed largely of water droplets. Higher up, where the temperature is well below freezing, the cloud is composed largely of ice crystals. In between lies the most important zone for hail formation: a region of supercooled water, water that remains liquid past its normal freezing point because it has nothing to freeze around. When ice particles fall through this zone, the supercooled water freezes on contact, adding a layer of ice to the falling particle. The growing hailstone is then caught by the updraft and carried back up to the top of the cloud, where a new layer of ice forms around it. The cycle repeats. The hailstone, when it is eventually too heavy for the updraft to support, falls to the ground. Cut open, a large hailstone shows concentric layers of ice, each one a record of a single pass through the cloud.

Once the storm is mature, several things happen at once. Rain begins to fall from the lower parts of the cloud, where the droplets have grown large enough to overcome the updraft. Hail falls from the upper parts, where the cycling has produced stones heavy enough to descend. And lightning begins within the cloud, generated by the separation of electrical charge that the turbulence of the system produces. Rain, hail, and lightning are not separate events. They are three outputs of the same system, each one tied to a different part of the cloud's structure. The Swedish meteorologist Tor Bergeron, working in the 1930s, was the first to describe how ice crystals and supercooled water coexist in the same cloud and produce precipitation through their interaction. The Bergeron–Findeisen process, as it became known, is the basis of the modern understanding of how a thunderstorm produces rain and hail at the same time.

Islamic Context
أَلَمْ تَرَ أَنَّ اللَّهَ يُزْجِي سَحَابًا ثُمَّ يُؤَلِّفُ بَيْنَهُ ثُمَّ يَجْعَلُهُ رُكَامًا فَتَرَى الْوَدْقَ يَخْرُجُ مِنْ خِلَالِهِ وَيُنَزِّلُ مِنَ السَّمَاءِ مِن جِبَالٍ فِيهَا مِن بَرَدٍ فَيُصِيبُ بِهِ مَن يَشَاءُ وَيَصْرِفُهُ عَن مَّن يَشَاءُ ۖ يَكَادُ سَنَا بَرْقِهِ يَذْهَبُ بِالْأَبْصَارِ
Do you not see that Allah drives clouds, then joins them together, then makes them into a mass, and you see the rain emerge from within it? And He sends down from the sky, from mountains within it, hail, and strikes with it whom He wills and averts it from whom He wills. The flash of its lightning almost takes away the eyesight.
— Quran 24:43

The verse depicts the formation of a storm as a continuing process. The verbs are all in the active present-tense in Arabic, the form used to describe ongoing action, not a single past event. Yuzjī (drives), yuʾallifu (joins), yajʾalu (makes), yakruju (emerges), yunazzilu (sends down). The verse is not saying that Allah once did these things. It is saying that the system is being operated, continuously, by the One whose name is the grammatical subject of each verb. The first verb, yuzjī (he drives gently), names the opening move. A softened form of the verb for moving forward, it depicts the clouds as being brought into being and set in motion, not as static features of the sky.

The stages of the process are linked by the conjunction thumma (then). The verse uses thumma three times in succession. Yuzjī saḥāban thumma yuʾallifu baynahu thumma yajʾaluhu rukāman (He drives clouds, then He joins between them, then He makes them into a piled mass). Al-Razi (d. 1210) noted that the choice of thumma rather than wa (and) is deliberate. Wa would link the stages in parallel. Thumma sequences them in time, each one following the previous. The verse is depicting a temporal order, not a list.

The third stage names the result. Thumma yajʾaluhu rukāman, then He makes it into a piled mass. The noun rukām is rare in the Qur’an. Al-Tabari (d. 923) and al-Qurtubi (d. 1273) both noted that the word denotes something heaped or layered, an accumulation rather than a single object. The verse is depicting the cumulating structure of a mature cloud, the heaped, piled-up body that develops when smaller masses converge and build vertically. The three stages of the verse, drive, join, pile, name three phases of a single continuing process.

From the piled mass, two outputs are described, each in the same continuing tense. Fatarā al-wadqa yakhruju min khilālihi, and you see the rain emerge from within it. The verb yakhruju (emerges) is active present-continuous. The rain is emerging as the verse is being read. Wa yunazzilu mina al-samāʾi min jibālin fīhā min barad, and He sends down from the sky, from mountains within it, hail. The verb yunazzilu (sends down) is the same form. Mujahid read the jibāl (mountains) as a description of the cloud's heaped shape rather than a literal reference to mountains in the sky. The rain and the hail are both outputs of the same continuing process, distinguished by which part of the system produces them.

The Connection

The Qur’anic sequence—clouds being driven, joined, and built into a piled mass before releasing rain and hail—mirrors the lifecycle of a mature cumulonimbus system. Modern meteorology identifies these as distinct phases of an evolving process, driven by the vertical growth of the cloud and the interaction between supercooled water and ice. By sequencing these actions and describing the cloud as a "piled mass" (rukām) from which hail is ejected, the text identifies the exact architecture of a storm as it produces precipitation.