neutral stability

neutral stability

[′nü·trəl stə′bil·əd·ē] (control systems) Condition in which the natural motion of a system neither grows nor decays, but remains at its initial amplitude. (meteorology) The state of an unsaturated or saturated column of air in the atmosphere when its environmental lapse rate of temperature is equal to the dry-adiabatic lapse rate or the saturation-adiabatic lapse rate respectively; under such conditions a parcel of air displaced vertically will experience no buoyant acceleration. Also known as indifferent equilibrium; indifferent stability.

neutral stability

Neutral stability.i. In meteorology, it is that condition in which the observed lapse rate is equal to the dry adiabatic lapse rate. A parcel of dry air will remain at its new level once it is pushed up because its temperature will be the same as that of the surrounding air.
ii. In aerodynamics, it means that an aircraft will tend to stay in its most recently commanded attitude or condition, without oscillations, and it will neither tend to return to its previous state or diverge from its new attitude. Also called neutral equilibrium or neutral static stability.