An updraft is wind blowing upward. We tend to think that wind usually blows sideways. However, in the sky, winds blow not only sideways, but also upward and downward in various directions.
Wherever clouds form, there is always an updraft. In other words, clouds are created by updrafts. In other words, air filled with water vapor is lifted upward by updrafts. The water vapor hidden in the air is then cooled in the sky and appears as water droplets, forming clouds.
Therefore, where there is an updraft, clouds form rapidly, while clouds disappear where the wind blows downward.
In and around clouds, there is always an upwind and a downwind, which causes clouds to form and disappear. This is the reason why clouds can form rapidly in some places and disappear rapidly in others.
When seen from a distance, the shape of the clouds appear to change.