8. Positive Lightning
Unlike bottom-oriented lightning, positive lightning is a strong and rather rare kind of lightning that starts from the top of a thunderstorm cloud. Positive lightning contains a positive charge unlike the more often occurring negative lightning, which charges the ground. Because of its high voltage and long duration, which can cause more serious damage than in negative lightning strikes, this kind of lightning is very hazardous. Often known as a “bolt from the blue,” positive lightning can strike many kilometres distant from the main thunderstorm and unexpectedly catch people and buildings. Although the exact processes behind positive lightning are unknown, it is thought to be connected to the top sections of major thunderstorm systems and may be involved in the starting of other kinds of lightning activity. Understanding the whole spectrum of lightning behaviour and enhancing safety measures for infrastructure and people depends on an awareness of positive lightning. Better predictive models and a better knowledge of the electrical dynamics inside thunderstorms can result from an analysis of the factors causing the generation of positive lightning.