By definition, all thunderstorms contain lightning. Lightning is a giant spark of electricity that occurs within the atmosphere or between the atmosphere and the ground. As lightning passes through the air, it heats the air rapidly to a temperature of about 50,000 degrees Fahrenheit, considerably hotter than the surface of the sun. During a lightning discharge, the sudden heating of the air causes it to expand rapidly. After the discharge, the air contracts quickly as it cools back to a normal temperature.
All thunderstorms go through various stages of growth, development, and dissipation.
On a warm summer day, as the sun heats the air, pockets of warmer air start to rise in the atmosphere. When these pockets reach a certain level in the atmosphere, cumulus clouds start to form. Continued heating can cause these clouds to grow vertically upward into the atmosphere. As the towering cumulus cloud continues to develop and grow, precipitation begins to form within the cloud, with snow in the upper levels of the cloud and rain in the lower levels of the cloud. The rapidly rising air in the cloud, combined with the movement of the precipitation within the cloud, cause electrical charges to build up within the cloud.