The science behind lightning and thunderstorm clouds, which occur inside thunderstorms, explains how they form. Thunderstorm clouds have a lot of air moving inside them, with updrafts and downdrafts transporting drops of rain and ice crystals to the top of the thundercloud, which can reach up to 70,000 feet above the ground. The energy builds, creating an electric field inside the cloud, which then needs to be released as a result of this discharge of energy. This energy heats the air rapidly, causing it to reach temperatures up to 50,000°F, which is five times hotter than the surface of the sun. The rapid expansion and contraction of the air is what creates the sound wave we hear as thunder.