Tsuki sumeba tani ni zo kumo wa shizumu meru mine fukiharau kaze ni shikarete

月澄めば谷にぞ雲は沈むめる
峰吹き払ふ風に敷かれて

Roma-ji: Tsuki sumeba tani ni zo kumo wa shizumu meru mine fukiharau kaze ni shikarete
English Translation: Since the moon shines clear,
down below into the valleys
the clouds seem to sink,
spread out flat beneath the wind
that sweeps across the peaks.
Meaning: Because the moon shines so clear, the clouds appear to have sunk into the valleys, pressed down flat by the wind that sweeps the peaks.
Commentary: Miscellaneous Poems 1106

Headnote continued from the preceding poem: "Composed on viewing the moon at a place called Shinsen in Ōmine"
Since the moon is clear, the clouds seem to have sunk into the valleys, flattened by the wind sweeping the peaks, the poet says; a vast scene viewed from on high, the peaks cleared by wind and bright with moonlight, the clouds spread over the valley floors.
The third of the moon poems at Shinsen, it follows the first two, on the moon's power to move and its reason, with an up-and-down contrast of moonlit peak and cloud-filled valley that conveys the viewpoint of an ascetic standing on the heights. It is a scene known only to those who practice in the mountains, gazing down on a sea of clouds.

First line, “tsuki sumeba”: because the moon is clear.
Second line, “tani ni zo kumo wa”: zo is emphatic, answered by the attributive meru in the third line.
Third line, “shizumu meru”: meru infers from sight, "they seem to sink"; the poem breaks here.
Fourth line, “mine fukiharau”: sweeping over the peaks, contrasting high and low.
Fifth line, “kaze ni shikarete”: pressed flat by the wind, the inversion giving the reason the clouds have sunk.
Author: Saigyō
Source: Sankashu
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