Troposphere

The troposphere is the lowest atmospheric layer,  containing 99% of the atmosphere's water vapor and aerosols, and approximately 70% of its mass.  This mass is mostly composed of stratus, cumulus, and altocumulus clouds.  The troposphere reaches approximately 11 miles above Earth's surface.  The 1 - 2 miles closest to the Earth's surface is known as the planetary boundary layer, and is where friction with the Earth's surface and interaction with landforms influences airflow.  As a result, most weather phenomena occur within the troposphere where air is in continual motion, with horizontal airflows and vertical currents.¹