(ii) Geshem (1653) - a shower: from a primitive root; to shower violently:
Belief in God's power to send the rain was not easy in an area like Palestine, where the timing, quantity, and distribution of rainfall were uncertain. The rainy season was synonymous with winter <Song 2:11; Prov. 26:1>, but it could begin any time from mid-October to January. It generally ended in April or early May. The early and latter rains were especially significant in the Old Testament period <Deut. 11:14; Joel 2:23>. The people longed for the rain <Jer. 14:4>, and waterless clouds were the source of frustration and irritation <Prov. 25:14; Jude 12>.
(from Nelson's Illustrated Bible Dictionary)
(Copyright (C) 1986, Thomas Nelson Publishers)
(iii) The preparatory work of the Holy Spirit through the Word etc.. to prepare hearts of people for growth.
(iv) (a) 2:11
(b) Ps 72:6