In general, which two factors determine the overall temperature of earth's atmosphere?

These two factors are:
*radiation coming into the Earth's atmosphere
*radiation going out the Earth's atmosphere

These two factors could be lumped into one natural phenomenon called the greenhouse effect. The Earth's atmosphere is a very unique characteristic in the solar system because it makes the planet livable. Without the atmosphere's work, the day would be too hot and the night would be too cold. The trapping of radiation, hence heat, keeps the overall temperature of the Earth.