Each updraft and downdraft in a thunderstorm is considered a separate unit called a convection cell. These cells are continually developing and dying if the conditions are right. A thunderstorm cell can last between 30 to 60 minutes. As one cell is dying, another could be forming. This increases the life, and dangerous weather, of a thunderstorm. 

We can break down each convection cell into three distinct stages; the cumulus stage, the mature stage, and the dissipating stage. 

umulus Stage 
The cumulus stage is the initial stage of thunderstorm development. This is when the updraft reaches the condensation point in the atmosphere and begins to form the cumulus cloud. During this stage, cumulus clouds can expand both vertically and laterally. In a short time, the clouds can reach 8 to 10 thousand meters in height, or around 30,000 feet. Cumulus clouds may also merge together during this vertical development, creating a single cloud that can cover an area of 5 to 10 miles. 

ature Stage 
The mature stage begins when the first drop of precipitation from the cumulus clouds reaches the ground. In the convection cycle, this is when the water droplets become too heavy for the updraft to hold aloft. 

During the mature stage, cloud tops begin to exceed 60,000 feet. Strong winds at these altitudes cause the tops of the clouds to level off, and take an anvil shape. The "anvil" is so high and temperatures are so low that the top of the cloud is composed entirely of ice crystals. 

A thunderstorm is strongest toward the end of the mature stage. Rain will be the heaviest and lightning is abundant. This is when hail, strong winds and even tornadoes may form. 

issipating Stage 
The dissipating stage is the end of a thunderstorm. This is when precipitation falls through the cloud, breaking it up. During the dissipating stage, the humidity in the air drops and the precipitation ends. 

 The animation above shows how updrafts and downdrafts work against each other in a thunderstorm.