The layer of the atmosphere that is closest to the Earth's surface is called the troposphere. The troposphere extends from the Earth's surface up to an altitude of approximately 7 to 20 kilometers (4 to 12 miles) above sea level, depending on the location and weather conditions.
The troposphere is where weather events occur, and it is the layer in which we live and breathe. It contains the majority of the Earth's atmospheric mass and is characterized by decreasing temperature with increasing altitude. On average, the temperature in the troposphere decreases by about 6.5 degrees Celsius per kilometer of altitude.
Above the troposphere, there are several other layers of the atmosphere, including the stratosphere, mesosphere, thermosphere, and exosphere. Each of these layers has its unique characteristics and plays a role in the Earth's atmospheric dynamics.