Just before lightning strikes Negative ions from a cloud reach down, in response to the electric field, positive charges rise up from buildings, trees. when they meet a path is formed for a bolt. Watch the upward discharge here from a lightning rod. Also the researchers captured on camera the moment when lightning rods on buildings released an upward discharge to attract incoming lightning: https://www.nytimes.com/2023/03/28/science/lightning-rod-video.html