Which atmospheric layer is known for stagnant air?

The stratosphere is characterized by temperature inversion, which occurs as altitude increases, leading to stagnant air conditions. In this layer, the temperature rises with height due to the absorption of ultraviolet radiation by the ozone layer. This inversion creates a stability that inhibits vertical mixing, which is a key feature of stagnant air. As a result, weather systems and turbulent air movement are typically confined to the lower troposphere, while the stratosphere remains largely undisturbed and stratified.

In contrast, the troposphere, which is the lowest layer of the atmosphere, is where most weather events occur, with active convection and mixing of air. The mesosphere and exosphere also do not have the characteristic stagnation found in the stratosphere; the mesosphere is known for decreasing temperatures with altitude and has limited air activity, while the exosphere, the outermost layer, primarily consists of very thin air with minimal interactions. Thus, the stratosphere's unique thermal structure is what makes it the layer associated with stagnant air conditions.