EPA 608 Technician Certification Practice Exam 2025 – Complete Study Resource

The mesosphere is recognized as the layer of Earth’s atmosphere situated above the stratosphere and below the thermosphere. This layer typically extends from about 30 miles (approximately 50 kilometers) to around 50 miles (approximately 85 kilometers) in altitude.

The selected answer indicates the starting point of the mesosphere, affirming that it begins at around 30 miles, which aligns with the established boundaries of this atmospheric layer. The importance of this information lies in the fact that the mesosphere is where most meteor burns occur, and understanding its altitude helps in appreciating the overall structure of the atmosphere.

While the other answer options mention various altitude ranges, they do not accurately reflect the accepted scientific parameters for the mesosphere. The first choice, for instance, suggests a range that starts below the acknowledged beginning of the mesosphere, while the second option extends the range beyond the typical upper limit of the mesosphere. The answer that emphasizes the boundary starting at 30 miles correctly captures the essence of the layer's definition.