The quality or condition of being unstable; lack of stability, firmness, or steadiness; liability to give way or to fail; insecurity; precariousness; as, the instability of a building.
Lack of determination of fixedness; inconstancy; fickleness; mutability; changeableness; as, instability of character, temper, custom, etc.
The atmosphere is in an unstable state when a displaced parcel of air continues to move either up or down, away from its initial location. Instability is necessary for convection to occur, and for the formation of thunderstorms.
The property of not being stable; thus, moving around over time, and/or uncertain in its movement over time.
(unstable air mass) A state in which the vertical distribution of temperature is such that an air particle, if given either an upward or downward impulse, will tend to move away with increasing speed from its original level.
Atmospheric condition where a parcel of air is warmer that the surrounding air in the immediate environment. This condition causes the parcel to rise in the atmosphere. Also see unstable atmosphere.
unreliability attributable to being unstable
the quality or attribute of being unstable and irresolute
A wavefunction is expressed as a long list of parameters (basis-set expansion) that are adjusted to minimize the total energy. Sometimes the global minimum is not obtained; the local minimum that is obtained may be unstable with respect to various perturbations or liberalization of constraints. Such a wavefunction is said to be unstable. One of the more common instabilities is an RHF to UHF instability, which indicates that the UHF solution (different alpha and beta orbitals) is of lower energy than the RHF solution (identical alpha and beta orbitals) for a closed-shell system. This may be encountered, for example, when a bond is stretched.
A condition where a parcel of air will move upward. Instability often results in the formation of cumulus clouds that may grow into thunderstorms.
A state of atmosphere in which the vertical distribution of temperature allows rising, warm air to continue to rise and accelerate. This kind of motion is conducive for thunderstorm development.
The tendency of an aeroplane to depart involuntarily from the set line of flight. Instability may express itself in yawing (swinging to right or left), rolling or porpoising (following an undulating path). Such faults may arise from a variety of causes, eg insufficient fin area, too short a fuselage, inefficient tailplane, failure to compensate in wing or aileron adjustment for the torque (twisting tendency) of the engine.
the tendency for an object, if moved, to accelerate in the direction of initial movement; in particular for meteorologists, the tendency for air parcels to accelerate upward after being lifted
A state of the atmosphere in which convection takes place spontaneously, leading to cloud formation and precipitation.
A state of the atmosphere where the vertical distribution of temperature is such that a parcel displaced from its initial position will continue to ascend.
Possessing the ability to move away from the original position; allows convection and enhances vertical motions.
The tendency for air parcels to accelerate when they are displaced from their original position; especially, the tendency to accelerate upward after being lifted. Instability is a prerequisite for severe weather - the greater the instability, the greater the potential for severe thunderstorms.
Occurs when a rising air parcel becomes less dense than the surrounding air. Since its temperature will not cool as rapidly as the surrounding environment, it will continue to rise on its own. Contrasts with stable air.
The state of equilibrium in which a parcel of air when displaced has a tendency to move further away from its original position. It is the condition of the atmosphere when spontaneous convection and severe weather can occur. Air parcels, when displaced vertically, will accelerate upward, often forming cumulus clouds and possibly thunderstorms.
Instability in systems is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be marginally stable or exhibit limit cycle behavior.