The thickness of the Earth's atmosphere is not precisely defined as it gradually thins out with increasing altitude. However, scientists generally consider the Earth's atmosphere to extend to an altitude of about 10,000 kilometers (6,200 miles) above the Earth's surface. Within this range, the atmosphere is divided into different layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
The majority of the Earth's atmospheric mass is concentrated in the lowermost layer, the troposphere, which extends from the Earth's surface up to an average altitude of about 11 kilometers (7 miles) at the poles and 17 kilometers (11 miles) at the equator. This layer is where weather occurs and where most of the Earth's air and water vapor are found.
Above the troposphere, the stratosphere extends to an average altitude of about 50 kilometers (31 miles). This layer contains the ozone layer, which plays a crucial role in absorbing harmful ultraviolet (UV) radiation from the Sun.
Beyond the stratosphere, the mesosphere extends to around 85 kilometers (53 miles) in altitude. The thermosphere follows, reaching up to about 600 kilometers (370 miles). In this region, the air density is extremely low, and the temperature increases with altitude due to the absorption of high-energy solar radiation.
Lastly, the exosphere, the outermost layer of the atmosphere, gradually transitions into the vacuum of space. It extends to approximately 10,000 kilometers (6,200 miles) above the Earth's surface.
It's important to note that the boundary between the Earth's atmosphere and outer space is not well-defined, as the density of gases continues to decrease gradually until it becomes indistinguishable from the interplanetary medium.
In summary, while the Earth's atmosphere does not have a well-defined "thickness," it is generally considered to extend up to around 10,000 kilometers (6,200 miles) above the Earth's surface, with the majority of its mass concentrated in the lower layers.