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

The highest layer of Earth's atmosphere, where temperatures begin to increase with altitude, is the Thermosphere. In this layer, solar radiation is absorbed by the sparse gas molecules, causing temperatures to rise significantly, often reaching thousands of degrees Celsius. This temperature increase occurs because the few particles that are present in the Thermosphere gain a lot of energy from solar radiation.

In contrast, the other layers of the atmosphere have different temperature trends. The Troposphere, which is closest to the Earth's surface, experiences a decrease in temperature with altitude. The Stratosphere also experiences a temperature increase, but it is located below the Thermosphere and is primarily where the ozone layer is found. The Mesosphere, which sits below the Thermosphere, has temperatures that decrease with altitude before reaching the warmer Thermosphere.

Understanding the characteristics of each atmospheric layer, particularly how temperature varies with altitude, helps clarify why the Thermosphere is identified as the correct answer in this context.