The Storm Armor skill for the Wizard says:
Bathe yourself in electrical energy, periodically shocking a nearby enemy for 175% weapon damage as Lightning. Lasts 10 minutes.
But what causes the "periodic shock of a nearby enemy"? Sometimes I've seen Storm Armor go off multiple times in rapid succession, sometimes it doesn't seem to go off for several seconds.
Is the shock rate related to attack speed?
(I realize the Reactive Armor and Shocking Aspect runes might change this behavior a bit, but I'm primarily interested in the base behavior.)