Troposphere

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. 

The transitional area between the troposphere and stratosphere is called the tropopause. The troposphere is made up of approximately 78% nitrogen, 21% oxygen, and 1% other gases, which include carbon dioxide, methane, neon, krypton, argon, helium, and hydrogen. The air in the troposphere is warmest closest to the earth and colder at higher elevations. Most of the dust particles in the earth's atmosphere are found in the troposphere.

 Other websites 
 Troposphere Citizendium

Category:Layers of Earth's atmosphere