Atmospheric stability determines whether a vertically displaced air parcel will tend to return to its original position (stable), keep moving (unstable), or stay put (neutral). It depends on comparing the adiabatic lapse rate with the actual temperature lapse rate.
Indicators
A stable atmosphere produces clear skies or stratiform clouds; an unstable one generates vertically developing clouds, showers, and thunderstorms. CAPE measures the energy available for convection. Soundings allow stability to be evaluated at each atmospheric layer.