Troposphere

 What precisely is the troposphere?

The troposphere is the atmosphere's innermost layer.

 The layer in which we live

The troposphere is closest to the Earth's surface. "Tropos" refers to change. This layer gets its name from the constantly changing weather that mixes up the gases in this part of our atmosphere.

 Depending on where you are on Earth, the troposphere is between 5 and 9 miles (8 and 14 kilometers) thick. The North and South Poles have the thinnest ice.

The air we breathe and the clouds in the sky are found in this layer. In this layer, the air is the densest. Indeed, the troposphere accounts for three-quarters of the total mass of the atmosphere. There is 78% nitrogen and 21% oxygen in the air here. Argon, water vapor, and carbon dioxide make up the remaining 1%.

 The troposphere is what you experience when you feel the wind on your face, see clouds in the sky, or watch a bird flap its wings in flight. It's a nice layer to live in.