If you mean by stability absent air currents, is because as one climb up through the layer of the atmosphere the air is thinner and less dense which is the driver of weather within the Earth’s atmosphere. read more
The stratosphere is the second layer of the atmosphere as we go upward. The troposphere, the lowest layer, is right below the stratosphere. The next higher layer above the stratosphere is the mesosphere. The stratosphere stretches between 15 and 50 kilometers up from the Earth's surface. read more