This verse quotes Psalm 104:4 to show that angels are messengers or servants. They have a lower rank than the Son, whom they serve.
In the Old Testament, angels are sometimes associated with winds and fire (see Exodus 3:2; Judges 6:21; 13:16, 20; 2 Samuel 22:11; Psalms 18:10; 35:5). This shows the angels’ connection with God’s rule over nature.