According to NASA, troposphere is the layer we call home.Closest to the surface of Earth, we have the troposphere. “Tropos” means change. This layer gets its name from the weather that is constantly changing and mixing up the gases in this part of our atmosphere.The troposphere is between 5 and 9 miles (8 and 14 kilometers) thick depending on where you are on Earth. It’s thinnest at the North and South Pole.
This layer has the air we breathe and the clouds in the sky. The air is densest in this lowest layer. In fact, the troposphere contains three-quarters of the mass of the entire atmosphere. The air here is 78% nitrogen and 21% oxygen. The last 1% is made of argon, water vapor, and carbon dioxide.
When you feel the wind on your face, see clouds in the sky, and watch a bird flap its wings in flight, you’re experiencing the troposphere. It’s a pretty nice layer to call home.
The troposphere has a direct contact with the Earth’s surface. It is therefore very sensitive to processes occurring at this level, like the evaporation of oceans, photosynthesis in plants, respiration of living creatures and human activities.

Troposphere Video

The troposphere differs from the stratosphere by the usually more rapid mixing of tropospheric air. One says that the troposphere is “turbulent”. This turbulence is partly connected to the “thermal profile” of the troposphere: the temperature decreases with the altitude, at an average of 6°C per kilometre.
This phenomenon favours the fast convection of air from the lowest layers to higher altitudes in the troposphere. This convection goes hand in hand with the formation of clouds, the so-called convective clouds.

Many molecules are more stable in the troposphere then elsewhere in the atmosphere.

Furthermore, the troposphere is protected from the hard ultraviolet radiation of the Sun by the higher layers of the atmosphere, namely by the stratospheric ozone layer. Because of this protection, many molecules are more stable in the troposphere then elsewhere in the atmosphere. This protection makes life possible on Earth.