Which layer of the atmosphere is closest to Earth's surface?

The troposphere is the layer of the atmosphere that is closest to Earth's surface, extending from the ground up to about 8 to 15 kilometers (5 to 10 miles), depending on the location and weather conditions. This layer plays a crucial role in supporting life, as it contains approximately 75% of the atmosphere's mass and the majority of its water vapor. Weather phenomena, including clouds, rain, and storms, occur within the troposphere, making it vital for climatic processes.

The stratosphere lies above the troposphere and contains the ozone layer, which absorbs and scatters ultraviolet solar radiation, but it is not where weather occurs. The mesosphere is higher up, generally extending from around 50 to 85 kilometers (31 to 53 miles) above the surface, where temperatures decrease with altitude. The thermosphere is even higher and characterized by increasing temperatures with altitude due to the absorption of high-energy solar radiation. Hence, the troposphere is distinctly different from these upper layers, functioning as the atmospheric layer that interacts directly with the Earth's surface and the living beings that inhabit it.