Why would an angel "command" Jesus to do something?

Revelation 14:14 And I looked, and behold a white cloud, and upon the cloud one sat like unto the Son of man, having on his head a golden crown, and in his hand a sharp sickle.

  15 And another angel came out of the temple, crying with a loud voice to him that sat on the cloud, Thrust in thy sickle, and reap: for the time is come for thee to reap; for the harvest of the earth is ripe.

If that is Jesus on the cloud, why would the angel speak to him like that?

Are there other instances of that, or perhaps it is not Jesus on the cloud, but only one who sat like unto the Son of man?