American Meteorological Society Certification (AMS) Practice

The correct answer identifies the thermosphere as the layer of the atmosphere that lies above the mesosphere. The atmosphere is structured in distinct layers, each characterized by specific temperature gradients and features. The thermosphere starts above the mesosphere, extending roughly from about 85 kilometers to between 600 and 1,000 kilometers above the Earth's surface.

In the thermosphere, temperatures can reach up to 2,500 °C or more, though this heat is not felt in the same way we experience warmth at lower altitudes, as the air density is extremely low. The thermosphere is where phenomena such as the auroras and the International Space Station's orbits occur.

In contrast, the stratosphere and the troposphere are layers located below the mesosphere. The stratosphere lies directly above the troposphere and below the mesosphere, while the troposphere is the lowest layer, where most weather events take place. The exosphere, which is the outermost layer, is located above the thermosphere and transitions into outer space. Understanding the hierarchy of atmospheric layers is crucial for grasping the complexities of meteorological and space phenomena.