Inside a thundercloud, ice and water bits rub together and build up electric charge. Plus gathers at the top, minus at the bottom — until a huge spark jumps down as a lightning bolt, heats the air so it explodes, and we hear the thunder.
Lightning — heat energy
Negative charge and rain
The sound we hear (thunder)
30,000°C
the bolt heats the air to almost 30,000 degrees in a blink
3 sec
thunder's sound takes 3 seconds to travel one kilometre
light first
light travels faster than sound, so we see the bolt before we hear the thunder