The tropopause ends at about 6-12 miles above the surface of Earth where it meets the stratosphere which is about 20 miles thick and reaches to about 30 miles above the surface of Earth. Clouds are accumulations of tiny water droplets in the lower atmosphere. They are of different shapes and even colors. Some are high in the sky. Others so low that they almost touch the ground.
Some days there are no clouds.
Clouds look quite substantial as we see them from the ground but they are composed of loosely spaced water droplets and are actually not very solid at all. They form when the composition and movement of an air mass creates the right conditions. Clouds form when moist air cools. We see these tiny droplets as clouds. If they are very close to the ground we see them as fog.