Western Governors University (WGU) SCIE1020 C165 Integrated Physical Sciences Practice Exam

The outermost layer of Earth's atmosphere is known as the exosphere. This layer extends from the upper boundary of the thermosphere out into space. In the exosphere, the atmospheric density is extremely low, meaning that the distance between individual gas molecules is quite large compared to layers below. This layer is characterized by the presence of very few particles, and those that are present can reach high velocities. The exosphere gradually fades into the vacuum of space and does not have a distinct upper boundary.

In contrast, the thermosphere lies beneath the exosphere and is notable for its dramatic temperature increase with altitude due to the absorption of high-energy solar radiation. The mesosphere is located below the thermosphere and is characterized by decreasing temperatures with height, while the stratosphere lies further down and contains the ozone layer, which absorbs and scatters ultraviolet solar radiation. Understanding these layers helps to illustrate the complex structure of Earth's atmosphere and the different conditions that exist at various altitudes.