"Do you not see that God drives the clouds, then gathers them together,
then piles them into a stack, then you see the rain coming out of them?"
Scientists have studied cloud types and have now come to know that rain clouds are formed and shaped according to definite systems and certain steps connected with certain types of wind and clouds.
One type of rain clouds are the cumulonimbus clouds associated with thunderstorms. Meteorologists have studied how cumulonimbus clouds are formed and how they produce rain, hail, and lightning. They have found that cumulonimbus clouds go through the following steps to produce rain:
1) The clouds are driven by the wind: Cumulonimbus clouds begin to form when wind drives small pieces of clouds (cumulus) to an area where these clouds converge.
2) Joining: The small clouds then join together forming a larger cloud.
3) Stacking: When the small clouds join together, updrafts within the larger cloud increase. The updrafts near the center of the cloud are stronger than those near the edges. These updrafts cause the cloud body to grow vertically, so the cloud is stacked up. This vertical growth causes the cloud body to stretch into cooler regions of the atmosphere where drops of water and hail formulate and begin to grow larger and larger. When these drops of water and hail become too heavy for the updrafts to support them, they begin to fall from within the cloud as rain, hail, etc.
Meteorologists have come to know these details of cloud formation, structure, and function through the use of planes, satellites, computers, balloons and the likes to study winds and its direction, to measure humidity and its variations, and to determine the levels and variations of atmospheric pressure. Since none of these facilities were available in the seventh century when the Quran was revealed, this information was not known at the time.
When we read the Quranic verse which describes this process we see a very precise scientific description of each of the steps which clouds go through before they produce the rain:
"Do you not see that God drives the clouds, then gathers them together, then piles them into a stack, then you see the rain coming out of them?" 24:43