How can angels be responsible for driving clouds and sending down rain by God's command, while humans have been able to send down rain through artificial cloud seeding?

You must desist from asking questions that raise doubts about the Qur’an and the Sunnah (definition). The imams severely reprimanded those who asked such questions and turned away from them, just as the Companions and the Successors did. For example, Omar ibn Al-Khattab punished Subaygh who asked about the ambiguous verses, and Malik ibn Anas answered a question about the modality of Allah's 'istiwa' (ascension) by stating that asking about it is an innovation. As for humans causing rain, this does not contradict the actions of angels, because both are by the decree of Allah.