165. Which is the region containing 3/4 of the mass of the atmosphere and to which are confined such phenomena as clouds, storms, precipitation and changing weather conditions?

The troposphere contains approximately three-quarters of the atmosphere's mass and is the region where weather phenomena such as clouds, storms, and precipitation occur. The stratosphere is above the troposphere and has limited weather activity. The stratopause and tropopause are boundary layers, not regions containing significant atmospheric mass or weather.