Here Allah explains how He creates the clouds that rain the water.

either from the sea, as was mentioned by more than one (of the scholars), or from whatever Allah wills.

means, He spreads them and causes them to increase and grow. From a little He makes a lot, and creates the clouds that look like shields. Then He spreads them out until they fill the horizon. Sometimes the clouds come from the sea, heavy and full, as Allah says:

And it is He Who sends the winds as heralds of glad tidings, going before His mercy. Till when they have carried a heavy-laden cloud, We drive it to a land that is dead until:

Similarly, We shall raise up the dead, so that you may remember or take heed.

Allah says here:

Mujahid, Abu ‘Amr bin Al-‘Ala’, Matar Al-Warraq and Qatadah said, “This means pieces.” Others said that it means ‘piled up,’ as Ad-Dahhak said. Others said that it means black, because they contained so much water, and sometimes they are heavy and close to the earth.

His saying:

means, ‘so you see the drops, i.e., the rain, which come from the midst of those clouds.’

They rejoice at the rain when it comes to them because of their need for it.

The people to whom this rain came were in despair, thinking that it rain would never fall, just before it came to them. When it came to them, it came at the time of greatest need, so it was a tremendous event for them What this means is that they were in need of it before it fell, and there had been no rainfall for a long time, so they were waiting for it at the time when it was due, but it did not come to them at that time. The rain was late, and a long time passed. Then the rain came to them suddenly, after they began to despair, and after their land became dry and barren, it was stirred to life, and it swelled and produced every lovely kind of growth. Allah says: