Rainmaker

It is the uncertainty of rainfall in southern California that doubtless makes this region attractive to the rainmaker. […] An examination into the methods of the rainmaker shows a disregard of physical laws, and a review of the history of rainmaking affords no proof of his success. By far the most important feature of his work consists in playing upon the credulity of mankind.

Source: wiktionary

By using a portable artificial "rainmaker" it is possible to obtain run-off data for rains of different amounts and intensities under a variety of conditions.

Source: wiktionary

Unlike summer, when scattered thunderstorms are the primary rainmaker, September precipitation becomes increasingly controlled by large but infrequent low pressure areas that develop near or migrate toward Colorado.

Source: wiktionary

Drought is the inherent vice of the climate of Africa, and the frequent destruction of the hopes of the husbandman which occurs from this cause, might have given origin to the function of "Rainmaker," among a less superstitious population. […] To procure rain, an ox is killed; the fat of it is chopped and mixed with different kinds of wood and leaves of trees; the whole are then burned. The secret of the business is to gain time by various artifices, until the rainmaker sees clouds arising in that direction from which rain generally comes.

Source: wiktionary