Scientists have debated over two main theories of how lightning starts for years.
Some say it's due to a build up of static electricity between particles in clouds, whereas others say cosmic rays are involved in the process.
Dr Michelle Dickinson joins Francesca Rudkin to breakdown these two leading theories.
LISTEN ABOVE

Miriam Margolyes: actress on her new movie Holy Days
13:48

Dr Lucy Hone: author and TED speaker on how to navigate tough times
16:22

Whitcoulls Recommends: Spies and other Gods and The Dead Speak
04:21