The idiom "大发雷霆" (dà fā léi tíng) is formed through a vivid metaphorical construction where "大发" (dà fā) means "to greatly unleash or issue forth," and "雷霆" (léi tíng) literally means "the rumble of thunder" or "thunderclap." Combined, the phrase paints a dramatic picture of someone unleashing anger with the sudden, explosive force and terrifying sound of a thunderstorm. This figurative formation draws from classical Chinese imagery that often equates a ruler's or superior's wrath with the power of celestial phenomena, thus semantically evolving to describe any person exploding into a furious rage.