'Cloud' in the Bible

and Jehovah said to Moses, Speak unto Aaron thy brother, that he come not at all times into the sanctuary inside the veil before the mercy-seat which is upon the ark, that he die not; for I will appear in the cloud upon the mercy-seat.

And he shall put the incense upon the fire before Jehovah, that the cloud of the incense may cover the mercy-seat which is upon the testimony, that he die not.