Atmosphere diagram showing the troposphere and other layers. The layers are not to scale.

The troposphere is the lowest layer of the Earth’s atmosphere. It extents up to 20 kilometers above the earth’s surface. It contains 75% of the atmosphere's mass and 99% of the total mass of water vapor and aerosols. This layer is rich in oxygen. The temperature drops from an average around 62°F (17°C) to -60°F (-51°C) at the troposphere.