Adam Clarke on Psalms 147:8

Who covereth the heaven with clouds - Collects the vapours together, in order to cause it to rain upon the earth. Even the direction of the winds, the collection of the clouds, and the descent of the rain, are under the especial management of God. These things form a part of his providential management of the world.

Maketh grass to grow upon the mountains - After this clause the Vulgate, the Septuagint, Ethiopic, Arabic, and Anglo-Saxon, add, and herb for the service of man. It appears that a hemistich, or half-line, has been lost from the Hebrew text; which, according to the above Versions, must have stood thus: ועשב לעבדת האדם veeseb laabodath haadam, as in Psa 104:14 : "And herbage for the service of mankind."