'Darkness' in the Bible

Then the LORD told Moses, "Stretch your hand toward the sky and there will be darkness over the land of Egypt, a darkness that one can feel."

So Moses stretched his hand toward the sky, and there was thick darkness in all the land of Egypt for three days.

coming between the camp of the Egyptians and the camp of Israel. The cloud remained there even in the darkness, illuminating the night, so that the one side did not come near the other all night.