Final answer:
The three criteria used for classification of the atmosphere are composition, temperature, and function, which explain the atmospheric formation, evolution, and role in climate processes.
Step-by-step explanation:
Three criteria used for classification of the atmosphere are composition, temperature, and function. This classification helps in understanding the way atmospheres on different planetary bodies form and evolve, their current states, and how they contribute to various climate processes.
The composition of Earth's atmosphere is primarily nitrogen (N2) and oxygen (O2), with trace gases such as water vapor (H2O), carbon dioxide (CO2), and ozone (O3).
The temperature of the atmosphere is a direct consequence of its composition and varies with altitude, influenced by the greenhouse effect and the distribution of solar energy.
Lastly, the function refers to the role the atmosphere plays in supporting life, controlling climate, and protecting living organisms from space radiation and meteoroids.
For example, Earth's atmosphere, with a surface pressure of 1 bar, is crucial for life, chemical evolution, and climate change. Atmospheric circulation (weather) is driven by sunlight and affects long-term climate variations like ice ages. Variations in Earth's orbit and axial tilt also play a significant role in these changes.