During a particularly stormy thunderstorm, Luna discovers that Jupiter and Clyde are afraid of thunder. She teaches them Daddy’s special trick for counting thunders to measure how far away the storm is getting, but it gets her wondering... How does Daddy’s trick work? Why is there more and more time between lightning and thunder as storms move away? To find out what’s happening, the trio make believe they’re little thunderclouds to find out what’s happening here.