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gently (raining); drizzling
moist; damp
雨あめがしとしとと降っふっている。
It's drizzling gently.
しとしとと降るふる雨あめの音おとが好きすき。
I like the sound of drizzling rain.
朝あさからしとしと雨あめが降りふり続くつづく。
The drizzle continues since morning.