In these verses the psalmist dwells on natural phenomena, which occur in obedience to Yahweh’s commands. Verse 15 speaks of Yahweh’s power to control the world by means of his command, which is quickly obeyed. In verse 15b his word runs swiftly represents Yahweh’s command as a swift messenger, taking Yahweh’s order quickly to its destination (so Die Bibel im heutigen Deutsch “his word quickly reaches its destination”). Good News Translation “and what he says is quickly done” may go beyond the meaning of the text, and it is recommended that Die Bibel im heutigen Deutsch serve as model. In verse 15b his word is the same as his command in verse 15a. If the passive must be avoided, one may say, for example, “He commands the earth and the earth obeys.”
In verse 16 snow is compared to wool; this may be a figure for the whiteness of snow (so Briggs; New English Bible), or else, as Good News Translation has it, “like a blanket”; frost is compared to “dust” (or, ashes). The word may have been chosen because of the wordplay in Hebrew: kepor kaʾeper for hoarfrost like ashes. In languages where snow and hoarfrost are unknown, it is possible to substitute other forms of precipitation such as “rain, drizzle, fog, dew.” The similarity of frost to ashes and “dust” may not be clear without saying, for example, “he scatters dew on the ground the way the wind blows dust.”
In verse 17 the word ice probably means hail; the figure is that of hailstones as large as pieces of bread, morsels (New Jerusalem Bible “breadcrumbs,” New Jerusalem Bible “crumbs”; see the word in Gen 18.5; Ruth 2.14). Good News Translation has used “gravel” as being more in keeping with the size and consistency of hailstones; New International Version “pebbles” may even be better.
In verse 17b instead of the Hebrew “in the presence of his cold, who can stand?” many commentators propose emending the text to read “in the presence of his cold the waters stand,” that is, they freeze solid (New English Bible, New American Bible, Biblia Dios Habla Hoy). The Hebrew text as it is makes sense; the emended text makes even better sense and prepares the way for the next verse. This is not to say, however, that the emended text should be used.
The reverse process is described in verse 18: at Yahweh’s command the ice melts, and moved (or, melted) by his wind (or, breath) the water flows once more. Here God’s wind (or, breath) is parallel with his word; both are the means whereby his will is done in the world. In languages where ice is unknown, verse 18 will have to be modified by saying, for example, “He gives a command and the dew disappears” or “… dries up.”
Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .