Information provided in the Qur'an about rain is that it is sent down to Earth in "due measure." This is mentioned in Surat az-Zukhruf as follows: It is He Who sends down water in measured amounts from the sky by which We bring a dead land back to life. That is how you too will be raised [from the dead]. (Quran chapter 43:11). This measured quantity in rain has again been discovered by modern research.

Note 57. Keith C. Heidorn, Ph.D., "Philipp Lenard: Brushing the Teardrops from Rain;" www.islandnet.com/~see/weather/history/lenard.htm