In Surah Az-Zukhruf (The Ornaments of Gold, 43:11), the Quran declares: "And He who sends down rain from the sky in measured amounts, and We revive thereby a dead land. Thus will you be brought forth."
The Arabic term used is biqadar (بقدر), meaning "with measure" or "according to a determined quantity." The Quran affirms that water descends from the sky in precise measure.
The historical context
In the 7th century, precipitation was perceived as a random and unpredictable phenomenon. The idea that rain falls "with measure" was counter-intuitive, especially in desert regions where rains are rare and irregular.
The scientific confirmation
Modern hydrology has revealed that precipitation is regulated by a precise and balanced water cycle:
- The water cycle: Water evaporates from the oceans, condenses into clouds, and falls back as precipitation. This cycle is regulated by complex mechanisms (solar radiation, temperature, winds) that maintain a global balance.
- The amount of water on Earth: The total amount of water on Earth has been constant for billions of years. Water is continuously recycled through the hydrological cycle, without significant loss or gain.
- The measurement of precipitation: Average annual precipitation on Earth is about 1 meter per year, distributed unevenly but regulated by major climate systems.
The Quranic verse also affirms that water "revives a dead land," which corresponds to the role of water in vegetation and life. Rain revives arid lands, a phenomenon well known in modern ecology.
The scientific significance
The Quran mentions the "measure" of rain 1,400 years before hydrology quantified the water cycle. This precision is all the more remarkable because the Quran was revealed in a desert region where rain is rare and precious.