instability"A property of the steady state of a system such that certain disturbances or perturbations introduced into the steady state will increase in magnitude, ...
Instability - 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 - 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 ...
INSTABILITY 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.
Instability (Unstable Air) 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.
Instability - Possessing the ability to move away from the original position; allows convection and enhances vertical motions.
Inversion - Temperatures increasing with increased altitude, or height. A negative lapse rate.
Instability: The tendency for air parcels to accelerate their motion when they are displaced from their original position; especially, the tendency to accelerate upward after being lifted by either topographical features, convergence, ...
instability: a state of the atmosphere when a parcel of air will keep moving either up or down from its starting position when moved. An unstable atmosphere is often associated with severe weather.
INSTABILITY (INSTBY)- Air that if lifted adequately will rise on its own due to positive buoyancy.
INTERPOLATION- Drawing an isopleth between known numerical values.
INVERSION (INV)- A temperature increase with height.
instability—A general term to indicate various states of the atmosphere in which spontaneous convection will occur when prescribed criteria are met; indicative of turbulence.
Instability- A state of the atmosphere in which convection takes place spontaneously, leading to cloud formation and precipitation.
Instability Line: A nonfrontal surface line or belt, along which convective instability occurs.
Intensification: In synoptic meteorology, the intensification of a high-pressure center means an increase in its central pressure in time.
Instability
A state of the atmosphere in which rising air is warmer than its surroundings and continues to rise.
Intertropical Convergence Zone ...
ABSOLUTE INSTABILITY
When the lapse rate of a column of air is greater than the dry adiabatic lapse rate. The term absolute is used because this applies whether or not the air is dry or saturated.
Related term: instability ...
Absolute Instability - The condition of air that has an environmental lapse rate that is greater than the dry adiabatic rate (1°C per 100 meters).
Absolute instability Property of an ambient air layer that is unstable for both saturated (cloudy) and unsaturated (clear) air parcels.
Baroclinic instability is a situation that results from the tight thermal gradients when air parcels are unstable to slantwise forcing.
POTENTIAL INSTABILITY- Also known as convective instability. Instability caused by dry air advecting over warm and humid PBL air. Lapse rate of temperature increases if lifting occurs.
CONDITIONAL INSTABILITY
Stable unsaturated air that will result in instability in the event or on the condition that the air becomes saturated. If the air is saturated, it is considered unstable; if air is unsaturated, it is considered stable.
Air in which static instability exists. This condition is determined by the vertical gradients of air temperature and humidity.
Updraught
Upward moving current of air of small dimensions. A rapidly moving vertical wind as found in thunderstorms.
Stability IndexThe overall stability or instability of a sounding is sometimes conveniently expressed in the form of a single numerical value. Used alone, it can be quite misleading, and at times, is apt to be worthless.
A thermodynamic chart thus is a useful tool in diagnosing atmospheric instability.
A common measure of atmospheric instability. Its value is obtained by computing the temperature that air near the ground would have if it were lifted to some higher level (around 18,000 feet, usually) and comparing that temperature to the actual ...
ACCAS clouds are a sign of instability aloft, and may precede the rapid development of thunderstorms.Accessory CloudA cloud which is dependent on a larger cloud system for development and continuance.
Delta Ts often are computed operationally over the layer between pressure levels of 700 mb and 500 mb, in order to evaluate the amount of instability in mid-levels of the atmosphere.
With the cap in place, air below it can continue to warm and/or moisten, thus increasing the amount of potential instability. Or, air above it can cool, which also increases potential instability.
High values indicate unstable and/or weakly-sheared environments; low values indicate weak instability and/or strong vertical shear.
This occurs even when the instability is excessive. A strong cap prevents widespread convection from occurring; thus, it allows low level heat and moisture to increase over a period of time. This in turn increases the amount of potential instability.
(Or gravitational or buoyant convection.) Motions that are predominantly vertical and driven by buoyancy forces arising from static instability, with locally significant deviations from hydrostatic equilibrium.
In what the Weather Service calls a ''perpetual war of instability and equilibrium'' the battle lines are drawn.
In hurricanes, condensation occurs through a process known as CISK (Convective Instability of the Second Kind). We will demonstrate CISK by referring to the animated cross-section through a mature hurricane given below.
ENERGY-HELICITY INDEX - An important instability and directional wind-shear index for determining the severity of thunderstorms based on the CAPE and helicity present in the storm environment.
Landspouts most often occur in drier areas with high based storms and considerable low-level instability. They generally are smaller and weaker than supercellular tornadoes though many persist in excess of 15 minutes and some have produced F3 damage.
All are formed within an unstable environment (see Q/A 2A.4), and all require the following to be in place: (i) Instability through a reasonable depth of the troposphere; preferably (but NOT necessarily) extending above the freezing level; ...
BUBBLE HIGH A small high that may be created by precipitation and vertical instability associated with thunderstorm activity. A product of downdrafts, it is relatively cold and often has the characteristics of a different air mass.
This is called convective instability.
The rising air now cools and the moisture in that air parcel begins to condense into ice crystals and clouds form.
Unstable air Air in which static instability prevails. This condition is determined by the vertical gradients of air temperature and humidity.
The tornado is fed by vertical instability of the atmosphere, covers a very small area, and has extremely high winds.
Unstable Air Mass
Air mass having static instability in its lower layers; convective clouds and precipitation occur if its moisture content is sufficiently high.
A sudden increase in wind speed, generally lasting from a few minutes up to half an hour. Line squalls are caused by instability of cold air moving over warmer water.
Logger
Device for recording digitised data.
Unlike tornadoes, whose parent clouds are cumulonimbus (thunderheads) and of great vertical depth, cold air funnels may drop from ordinary cumulus clouds as a result of small scale local instability aloft.
Dry Line - A boundary which separates warm, dry air from warm, moist air. The differences in the two air masses may be significant. The dry line is usually a boundary of instability along which thunderstorms form.
Conditionally unstable air An atmospheric condition that exists when the environmental lapse rate is between the dry adiabatic rate and the moist adiabatic rate. Also called conditional instability.
convectionVertical motion within the atmosphere due to thermal instability, with important impacts on the type cloud systems that can develop.
 See also: Stability, Air, Cloud, Temperature, Surface
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