instability The atmospheric condition in which displaced air tends to maintain its movement away from its original level. This occurs, for example, when rising air cools at the moist-adiabatic lapse rate while a greater environmental lapse rate allows the air parcel to remain warmer than surrounding air (or even increases the temperature difference) so that continual buoyancy prevails. See also conditional instability; potential instability; and stability.

instability Atmospheric condition in which displaced air tends to maintain its movement away from its original level. This occurs, for example, when rising air cools at the moist-adiabatic lapse rate while a greater environmental lapse rate allows the air parcel to remain warmer than surrounding air (or even increases the temperature difference) so that continual buoyancy prevails. See also CONDITIONAL INSTABILITY; POTENTIAL INSTABILITY; and STABILITY.

in·sta·bil·i·ty / ˌinstəˈbilitē/ • n. (pl. -ties) lack of stability; the state of being unstable: political and economic instability. ∎  tendency to unpredictable behavior or erratic changes of mood: she showed increasing signs of mental instability.