Where does the troposphere start?

Answer 1

The troposphere is the lowest layer of the atmosphere. It starts on the surface of the planet and it is comprised of nitrogen and oxygen.

Answer 2

The troposphere starts at the Earth's surface and extends to an average altitude of about 7-17 kilometers (4-10 miles) depending on the location. It is the lowest layer of the Earth's atmosphere and contains the majority of the atmosphere's mass as well as where weather events primarily occur.