The phrase “a son of man” underlines the humanity of the cloud’s passenger. It should be noted that though with today’s technology mankind is able to reach the clouds (and beyond), none of our technology allows us to “sit” on a cloud, let alone use a cloud as a means of transportation (see Psalm 104:3). But here is a “son of man” (human) seated on a cloud (and he is not tumbling through and falling to earth).
14 Then I looked, and behold, a white cloud, and seated on the cloud one like a son of man, with a golden crown on his head, and a sharp sickle in his hand.