These have the samchut  authority  to shut Shomayim, that no geshem  rain  may fall during the days of the nevu'ah  prophecy  of them. And samchut  authority  they have over the waters to  turn them into dahm and to strike ha'aretz with makkot of every kind, as often as they want.  [Shemot 7:17,19 [Melachim Alef 17:1]