وَأَرْسَلْنَا الرِّيَاحَ لَوَاقِحَ
And We send the winds fertilizing.
i.e., fertilizing the clouds so that they give rain, and fertilizing the trees so that they open their leaves and blossoms.
These winds are mentioned here in the plural form because they give results, unlike the barren wind (Ar-Rih Al-'Aqim, see Adh-Dhariyat 51;41), which is mentioned in the singular and described as barren since it does not produce anything; because results can only be produced when there are two or more things.
Abdullah bin Mas`ud said,
"The wind is sent bearing water from the sky, then it fertilizes the clouds until rain begins to generously fall, just as the milk of the pregnant camel flows generously."
This was also the opinion of Ibn Abbas, Ibrahim An-Nakha`i and Qatadah.
Ad-Dahhak said;
"Allah sends it to the clouds and it gets fertilized and becomes full of water."
Ubayd bin Umayr Al-Laythi said;
"Allah sends the wind which stirs up the earth, then Allah sends the wind which raises clouds, then Allah sends the wind which forms clouds, then Allah sends the fertilizing wind which pollinates the trees."
Then he recited,
وَأَرْسَلْنَا الرِّيَاحَ لَوَاقِحَ
(And We sent the winds fertilizing).
Fresh Water is a Blessing from Allah
Allah says;
فَأَنزَلْنَا مِنَ السَّمَاء مَاء
then We cause the water to descend from the sky,
فَأَسْقَيْنَاكُمُوهُ
and We give it to you to drink,
This means, "and We send it down to you fresh and sweet, so that you can drink it; if We had wished, We could have made it salty (and undrinkable)", as Allah points out in another Ayah in Surah Al-Waqi`ah, where He says;
أَفَرَءَيْتُمُ الْمَأءَ الَّذِى تَشْرَبُونَ
أَءَنتُمْ أَنزَلْتُمُوهُ مِنَ الْمُزْنِ أَمْ نَحْنُ الْمُنزِلُونَ
لَوْ نَشَأءُ جَعَلْنَـهُ أُجَاجاً فَلَوْلَا تَشْكُرُونَ
Tell Me! The water that you drink, is it you who cause it to come down from the rain clouds, or are We the cause of it coming down! If We willed, We verily could make it salty (and undrinkable), why then do you not give thanks (to Allah)! (56;68-70)
And Allah says;
هُوَ الَّذِى أَنْزَلَ مِنَ السَّمَاءِ مَأءً لَّكُم مَّنْهُ شَرَابٌ وَمِنْهُ شَجَرٌ فِيهِ تُسِيمُونَ
He it is Who sends water down from the sky; from it you drink and from it (grows) the vegetation on which you send your cattle to pasture. (16;10)
وَمَا أَنتُمْ لَهُ بِخَازِنِينَ
and it is not you who are the owners of its supply.
The meaning is, "You are not taking care of it; rather We send it down and take care of it for you, making springs and wells flourish on the earth."
If Allah so willed, He could make it disappear, but by His mercy He sends it down and makes it fresh and sweet, maintaining the springs, wells, rivers and so on, so that they may drink from it all year long, water their livestock and irrigate their crops.
The Power of Allah to initiate and renew Creation
Allah says