Out of whose womb came the ice? - That is, who has caused or produced it? The idea is, that it was not by any human agency, or in any known way by which living beings were propagated.
And the hoary frost of heaven - Which seems to fall from heaven. The sense is, that it is caused wholly by God; see the notes at Job 37:10.

Out of whose womb came the ice? - Ice is a solid, transparent, and brittle body, formed of water by means of cold. Some philosophers suppose that ice is only the re-establishment of water in its natural state; that the mere absence of fire is sufficient to account for this re-establishment; and that the fluidity of water is a real fusion, like that of metals exposed to the action of fire; and differing only in this, that a greater portion of fire is necessary to one than the other. Ice, therefore, is supposed to be the natural state of water; so that in its natural state water is solid, and becomes fluid only by the action of fire, as solid metallic bodies are brought into a state of fusion by the same means. Ice is lighter than water, its specific gravity being to that of water as eight to nine. This rarefaction of ice is supposed to be owing to the air-bubbles produced in water by freezing, and which, being considerably larger in proportion to the water frozen, render the body so much specifically lighter; hence ice always floats on water. The air-bubbles, during their production, acquire a great expansive power, so as to burst the containing vessels, be they ever so strong. See examples in the note on Job 37:10 (note).
The hoary frost of heaven, who hath gendered it? - Hoar-frost is the congelation of dew, in frosty mornings, on the grass. It consists of an assemblage of little crystals of ice, which are of various figures, according to the different disposition of the vapours when met and condensed by the cold. Its production is owing to some laws with which we are not yet acquainted. Of this subject, after the lapse and experience of between two and three thousand years, we know about as much as Job did. And the question, What hath engendered the hoar-frost of heaven! is, to this hour, nearly as inexplicable to us as it was to him! Is it enough to say that hoar-frost is water deposited from the atmosphere at a low temperature, so as to produce congelation?

Out of whose womb came the ice?.... The parent of the rain and dew is the parent of the ice also, and he only; it is therefore called "his ice", his child, his offspring, Psalm 147:17. Here the Lord is represented as a mother, and so he is by Orpheus (b) called "metropator", or "mother-father";
and the hoary frost of heaven, who hath gendered it? this is of God, and by his breath; see Job 37:10.
(b) Apud Clement. Stromat. l. 5. p. 608.

Job 37:10.