tn The Hebrew word refers to an expanse of air pressure between the surface of the sea and the clouds, separating water below from water above. In v. 8 it is called “sky.”

sn An expanse. In the poetic texts the writers envision, among other things, something rather strong and shiny, no doubt influencing the traditional translation “firmament” (cf. NRSV “dome”). Job 37:18 refers to the skies poured out like a molten mirror. Dan 12:3 and Ezek 1:22 portray it as shiny. The sky or atmosphere may have seemed like a glass dome. For a detailed study of the Hebrew conception of the heavens and sky, see L. I. J. Stadelmann, The Hebrew Conception of the World (AnBib), 37–60.

tn Heb “the waters from the waters.”