فَتَرَكْنَ كُلَّ قَرَارَةٍ كَالدِّرْهَمِ
The clouds left every hollow like a dirham.
A qarārah is a small depression. The shape and shine of water in it evoke a silver coin. The comparison is not to a vast flood; it is to many small, mirror-like gleams.
Kulla (“every”) extends the picture over the whole meadow. Countless tiny reflections provide a visual counterpart to the freshness already described.