And God said: Let there be a firmament made amidst the waters: and let it divide the waters from the waters.
Sforno
"Let there be a firmament in the midst of the water" - let there be a [manifestation of] nature in the midst of elemental water similar to a sphere in their midst all around, separating by form part of them [i.e., the elemental waters] from the other part of them, in such a fashion that the upper part of the waters, near the [upper] atmosphere [lit.: air], would turn into vapor. Now behold, thereby, they [the waters] necessarily ascended to some boundary in the elemental air, and the air necessarily was subject to some transformation which made a place for a portion which was converted to vapor, and it expanded to a place much great in volume than its original place.
Hebrew and Aramaic words are the commentator’s citations of the sacred text; the English translation that follows each is the translator’s.
Imported from an open dataset — not yet checked against the printed edition.