ἴσως οὖν λέγει, ὥσπερ ἂν εἰ εἴποι πνευματόρρουν, ‘ἀητόρρουν’ ὅθεν δὴ βούλεται αὐτὸν οὕτως εἰπεῖν, ὅτι ἐστὶν ἀήρ.
Besides the translation from Perseus, I have consulted that of Jowett; also one in Russian and one in French. All of them skip this phrase: Perhaps the poet means to say “air-flow” (ἀητόρρουν), as he might say “wind-flow” (πνευματόρρουν) (from Perseus); he who uses the term may mean, so to speak, air-flux (aetorroun), in the sense of wind-flux (pneumatorroun); and because this moving wind may be expressed by either term he employs the word air. (by Jowett).
My suggestion: Perhaps [a poet] may say ‘air-flow’, as if he were saying ‘wind-flow’, since [it] is air, for what reason he wants to call it thus. How can it be improved?