Genesis 1:6

“And God said, let there be a firmament in the midst of the waters, etc.] On which the Spirit of God was sitting and moving, (<010102>Genesis 1:2) part of which were formed into clouds, and drawn up into heaven by the force of the body of fire and light already produced; and the other part left on the earth, not yet gathered into one place, as afterwards: between these God ordered a “firmament to be”, or an “expanse” f51; something stretched out and spread like a curtain, tent, or canopy: and to this all those passages of Scripture refer, which speak of the stretching out of the heavens, as this firmament or expanse is afterwards called; (see <19A402>Psalm 104:2 <234022>Isaiah 40:22 42:5) and…”

“SECOND DAY. (Gen 1:6-8) firmament--an expanse--a beating out as a plate of metal: a name given to the atmosphere from its appearing to an observer to be the vault of heaven, supporting the weight of the watery clouds. By the creation of an atmosphere, the lighter parts of the waters which overspread the earth's surface were drawn up and suspended in the visible heavens, while the larger and heavier mass remained below. The air was thus "in the midst of the waters," that is, separated them; and this being the apparent use of it, is the only one mentioned, although the atmosphere serves other uses, as a medium of life and light.”

“- IV. The Second Day 6. רקיע rāqı̂ya‛, “expanse;” στερέωμα stereōma, רקע rāqa‛, “spread out by beating, as leaf gold.” This expanse was not understood to be solid, as the fowl is said to fly on the face of it Genesis 1:21. It is also described as luminous Daniel 12:3, and as a monument of divine power Psalms 150:1. 7. עשׂה ‛āśâh “work on,” “make out of already existing materials.” The second act of creative power bears upon the deep of waters, over which the darkness had prevailed, and by which the solid crust was still overlaid. This mass of turbid and noisy water must be reduced to order, and confined within certain limits, before the land can be reached. According to the laws of…”

“We have here an account of the second day's work, the creation of the firmament. In which observe, 1. The command of God; Let there be a firmament - An expansion; so the Hebrew word signifies, like a sheet spread, or a curtain drawn out. This includes all that is visible above the earth, between it and the third heavens, the air, its higher, middle, and lower region, the celestial globe, and all the orbs of light above; it reaches as high as the place where the stars are fixed, for that is called here the firmament of heaven, Gen 1:14-15, and as low as the place where the birds fly for that also is called the firmament of heaven, Gen 1:20. 2. The creation of it: and God made the firmament.…”

“1:6-8 The creation account describes the appearance of things from a human perspective. The sky is viewed as a shiny dome that is a buffer between two collections of water (cp. Job 37:18; Ezek 1:22). In the ancient Near East, the cosmos was understood as a three-tier system, with rain originating from the outermost tier (see Gen 7:11-12 and study note).”

“Let there: Gen 1:14, Gen 1:20, Gen 7:11, Gen 7:12; Job 26:7, Job 26:8, Job 26:13, Job 37:11, Job 37:18, Job 38:22-26; Psa 19:1, Psa 33:6, Psa 33:9; Psa 104:2, Psa 136:5, Psa 136:6, Psa 148:4, Psa 150:1; Ecc 11:3; Jer 10:10, Jer 10:12, Jer 10:13, Jer 51:15; Zac 12:1 firmament: Heb. expansion Genesis 1:7”

“The Second Day. - When the light had been separated from the darkness, and day and night had been created, there followed upon a second fiat of the Creator, the division of the chaotic mass of waters through the formation of the firmament, which was placed as a wall of separation ( ) in the midst of the waters, and divided them into upper and lower waters. .s, from to stretch, spread out, then beat or tread out, means expansum, the spreading out of the air, which surrounds the earth as an atmosphere. According to optical appearance, it is described as a carpet spread out above the earth (Psa 54:2), a curtain (Isa 40:22), a transparent work of sapphire (Exo 24:10), or a molten looking-glass…”