What phenomenon is characterized by temperature increases with altitude and non-uniform gas distribution?

The phenomenon characterized by temperature increases with altitude and non-uniform gas distribution is the thermosphere. In the thermosphere, which is the highest layer of the Earth's atmosphere, temperatures can rise significantly due to the absorption of very high-energy ultraviolet and X-ray radiation from the sun. This results in a temperature profile where, unlike in the troposphere, stratosphere, and mesosphere, temperatures increase with height.

Additionally, the thermosphere has a very thin atmosphere where gases are much more spread out compared to the lower atmospheric layers, creating a non-uniform distribution of gases. This layer is also known for the presence of ionized particles, leading to phenomena such as the auroras. These characteristics distinctly differentiate the thermosphere from the other atmospheric layers, making it the correct choice for this question.