what is Troposphere?

We live on the Earth where different types of layers are found. Troposphere is one of them. It is the lowest layer. It contains 75% of the atmosphere's mass and 99% of the total mass of water vapour and aerosols. The lowest part of troposphere is called planetary boundary layer. The word troposphere is derived from tropos meaning "turn toward" and sphere means Earth. It directly symbolises different weather conditions.