What is the difference between stable and unstable air?

This is referred to as stable air. If a rising parcel of air is warmer than the surrounding atmosphere it will continue to rise. This is because warm air is less dense or lighter than cool air. This is referred to as unstable air, please mark as brainliest!

In the atmosphere, whether air that is displaced does so in an unstable or stable environment depends upon the vertical temperature profile of the air  its lapse rate  and upon the moisture content of the parcel. These differences are fundamental to understanding why clouds take up the form they do.