Why do we have thunder storms

Thunderstorms happen when cold air sinks and hot air rises in rapid succession. There has to be an unstable body of hot air for a thunderstorm to happen. Cool air mingles with the hot air causing condensation (that means that raindrops form) This makes a cumulous cloud.

The moisture in the cloud is either positively charged or negatively charged. Negatively charged particles sink to the bottom of the cumulous cloud while positively charges particles rise. The positive and negative charges rub together and spark causing lightning.

Thunder is formed by the lightning, a bolt of lightning is hollow, and has no air inside it. When the lightning dissipates the air rushes to fill the space breaking the sound barrier in the process, this creates the boom.