Allah sends the winds as heralds of glad tidings, i.e., they bring the clouds behind them. The winds are of many different types, depending on the purpose for which they are sent. Some of them form the clouds, others carry the clouds or drive them, and others come ahead of the clouds as heralds announcing their coming. Some of them come before that to stir up the earth, and some of them fertilize or "seed" the clouds to make it rain. Allah says:
وَأَنزَلْنَا مِنَ السَّمَآءِ مَآءً طَهُوراً
(and We send down pure water from the sky), meaning, as a means of purifying it. Abu Sa`id said, "It was said: "O Messenger of Allah, can we perform Wudu' with the water of the well of Buda`ah For it is a well in which rubbish and the flesh of dogs are thrown. He said:
«إِنَّ الْمَاءَ طَهُورٌ لَا يُنَجِّسُهُ شَيْء»
(Water is pure and nothing makes it impure.) This was recorded by Ash-Shafi`i and Ahmad, who graded it Sahih, and also by Abu Dawud and At-Tirmidhi, who graded it Hasan, and by An-Nasa'i. His saying:
لِّنُحْيِىَ بِهِ بَلْدَةً مَّيْتاً
(That We may give life thereby to a dead land,) means, a land that waited a long time for rain. It is devoid of vegetation or anything at all. When the rain comes to it, it becomes alive and its hills are covered with all kinds of colorful flowers, as Allah says:
فَإِذَآ أَنزَلْنَا عَلَيْهَا الْمَآءَ اهْتَزَّتْ وَرَبَتْ
(but when We send down water to it, it is stirred to life and growth...) (41:39). His saying:
وَنُسْقِيَهِ مِمَّا خَلَقْنَآ أَنْعَـماً وَأَنَاسِىَّ كَثِيراً
(and We give to drink thereof many of the cattle and men that We had created. ) means, so that animals such as cattle can drink from it, and people who are in desperate need of water can drink from it and water their crops and fruits. This is like the Ayah:
وَهُوَ الَّذِى يُنَزِّلُ الْغَيْثَ مِن بَعْدِ مَا قَنَطُواْ
(And He it is Who sends down the rain after they have despaired,) (42:28)
فَانظُرْ إِلَى ءَاثَـرِ رَحْمَةِ اللَّهِ كَيْفَ يُحْىِ الاٌّرْضَ بَعْدَ مَوْتِهَآ
(Look then at the effects of Allah's mercy, how He revives the earth after its death.) (30:50) His saying:
وَلَقَدْ صَرَّفْنَـهُ بَيْنَهُمْ لِيَذَّكَّرُواْ
(And indeed We have distributed it among them in order that they may remember) means, `We cause rain to fall on this land and not on that, and We cause the clouds to pass over one land and go to another, where We cause sufficient rain to fall so that its people have plenty, but not one drop falls on the first land.' There is a reason and great wisdom behind this. Ibn `Abbas and Ibn Mas`ud, may Allah be pleased with them said: "One year does not have more rain than another, but Allah distributes the rain as He wills. Then he recited this Ayah:
وَلَقَدْ صَرَّفْنَـهُ بَيْنَهُمْ لِيَذَّكَّرُواْ فَأَبَى أَكْثَرُ النَّاسِ إِلاَّ كُفُوراً
(And indeed We have distributed it (rain or water) amongst them in order that they may remember the grace of Allah, but most men refuse (out of) ingratitude. )" meaning, so that they may be reminded, when Allah brings the dead earth back to life, that He is able to bring the dead and dry bones back to life, or that those from whom rain is withheld are suffering this because of some sin they have committed, so that they may give it up.
فَأَبَى أَكْثَرُ النَّاسِ إِلاَّ كُفُورًا
(but most men refuse (out of) ingratitude.) `Ikrimah said, "This refers to those who say that rain comes because of such and such a star." This view of `Ikrimah is similar to the authentic Hadith recorded in Sahih Muslim; one day after a night's rain, the Messenger of Allah ﷺ said to his Companions:
«أَتَدْرُونَ مَاذَا قَالَ رَبُّكُمْ؟»
(Do you know what your Lord says) They said: "Allah and His Messenger know best." He said:
«قَالَ: أَصْبَحَ مِنْ عِبَادِي مُؤْمِنٌ بِي وَكَافِرٌ، فَأَمَّا مَنْ قَالَ: مُطِرْنَا بِفَضْلِ اللهِ وَرَحْمَتِهِ فَذَاكَ مُؤْمِنٌ بِي، كَافِرٌ بِالْكَوْكَبِ، وَأَمَّا مَنْ قَالَ: مُطِرْنَا بِنَوْءِ كَذَا وَكَذَا، فَذَاكَ كَافِرٌ بِي، مُؤْمِنٌ بِالْكَوْكَب»
(He says: "This morning some of My servants became believers in Me, and some became disbelievers. As for the one who said, `We have been given rain by the mercy and grace of Allah,' he is a believer in Me and a disbeliever in the stars. As for the one who said, `We have been given rain by such and such a star,' he is a disbeliever in Me and a believer in the stars.")