What is a cloud like formation in metaphysical/paranormal activity?

While searching for ghosts/spirits, a friend of mine detected a human spirit in my part of the house. My friend can also see auras, is empathic, and can see other anomalies of the metaphysical realm such as weird sparks, electrical energies, and so on. But she mentioned after seeing this melancholy spirit linger in my home, she also spotted a strange cloud-like formation of energy in the center of the room, and had never seen something like it before. As far as she can detect, it wasn't human, didn't give off any dangerous presence (neither did the spirit) and it slowly moved toward the ceiling, then disappeared. I suppose it was like the electrical energy she's seen before, but with different characteristics...What is it and why would it occur in my home? Any suggestions or spiritual insight would be helpful, Thanks.