First colour image of sprite lightning, labelled version. The altitude is labelled in kilometres at left. Red sprites typically extend from above a thunderstorm up to the ionosphere at 95 kilometres altitude. Red sprites last for a few milliseconds and are barely visible to the naked eye. Their formation is associated with the most energetic positive-charge cloud-to-ground lightning strikes that can leave uncompensated negative charge. This charge creates quasi-electrostatic fields and causes ionization and light emission. Photographed on 4 July 1994 over the USA during a NASA-sponsored project through the University of Alaska Fairbanks (UAF).