The gaseous envelope around the earth is known as atmosphere. The lowest layer of this is extended upto 10 km from sea level, this layer is

1. Stratosphere 

2. Troposphere

3. Mesosphere

4. Hydrosphere

Troposphere is the lowest region of the atmosphere. It extends upto the height of -10km from sea level. Troposphere is a turbulent, dusty zone containing air, much water vapour and clouds.