Why do scientists decided where one layer of the atmosphere ended and the next one began?

Scientists determine the boundaries between atmospheric layers based on changes in temperature, composition, and pressure with altitude. These transitions, known as "pauses," reflect distinct physical and chemical properties that affect atmospheric behavior, such as the troposphere's temperature decrease with height compared to the stratosphere's temperature increase. By studying these characteristics, scientists can define layers like the troposphere, stratosphere, mesosphere, and thermosphere, which play crucial roles in weather patterns, climate, and atmospheric dynamics.