Floating to the southeast, below cloud level, varying brightness, reacted to a plane coming it's way

There was one light to the southeast, likely over lake ontario, around 11.15pm.
Very windy night, cloud cover was passing over.  Was at a high altitude but below cloud. I could see it pass through clouds.  Light went from dim to very bright to nearly unseeable to bright again.  It hovered but was moving around slowly in one area.  A plane was approaching from the north, northeast, below clouds.  The light slowly ascended as plane flew by. After plane had passed it dropped quickly. The light dimmed, or it moved into the clouds, and I could no longer see it.