light rain, short while
霎 centers on a brief, light atmospheric event: a passing drizzle or a fleeting moment. The two senses are connected by the idea of something transient and delicate.
霎 combines 雨 (rain) with 妾, which likely contributes the sound and may suggest something fleeting or secondary, fitting the idea of a brief light rain. The exact historical development is uncertain.
Rain 雨 falls briefly on a concubine 妾, who is only outside for a short while, capturing both the light rain and the fleeting moment.
For ショウ, imagine a short, light rain shower: the word 'shower' begins with 'sho', cueing ショウ, and the rain is brief like the kanji's meaning.