How does air affect earths atmosphere

Air is a mixture of gases and atmosphere contains different layers of these gases.So,air only forms the atmosphere.
But atmosphere is not homogeneous.It contains different air masses like cold airmass,warm airmass etc.The interaction of these masses produces weather systems thus affecting the atmosphere.So atmosphere becomes turbulent sometimes because of these airmasses. even tho the atmosphere is air and air is the atmosphere meaning it allows living things to breathe

  like australopithecus afarensis; probably the direct ancestor of this group. africa: 5.8 to 4.4 million years ago.