How long does it take for the average cumulus cloud to disperse

Cumulus clouds have a life time of about 5 minutes in which they disperse.

Explanation:

The puffy, fluffy, impulsive clouds that we gaze upon on sunny days, that might become quite dramatic when they grow into huge, stormy thundering clouds. They have a short lifespan because they cause the air around them to cool (and sink) which inhibits its growth so it will eventually give off all its moisture and ceases to exist. It develops from bottom to top in vertical direction, which is different from others.