In this image is shown the cloud produced by an Alaskan volcano. The cloud rose all the way into the stratosphere. Along the way it encountered a boundary which is probably the tropopause. When the cloud encountered the boundary it flattened out. This flattening can clearly be seen in the picture.
This image shows that there are distinct layers or regions to the atmosphere. The regions are called the troposphere, stratosphere, mesosphere, and thermosphere. Then there is the ionosphere which is the region of the atmosphere that is filled with charged particles.