“What makes a thunderstorm?”
Thunderstorms need three things to form: moisture, instability and lift. Instability forms from daytime heating of the earth’s surface heating the air around it causing it to rise because warm air is lighter than cool air, this is called the updraft. When there’s enough moisture that rising air can start to form clouds and with enough lift it can tap into instability aloft with allows cumulonimbus clouds to form. Cool air starts to enter the cloud and since cool air is heavier than warm air, the air starts to descend, this is called the downdraft. Water droplets inside the cloud eventually get too large for the updraft to keep up and the water falls to the ground as rain in the downdraft.
Water droplets and ice particles collide within the cloud separating an electron from these molecules, and the cloud can become charged. Lightning occurs as an electrical discharge from the cloud and thunder is the resulting sound of this discharge.