convective instability


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convective instability

[kən′vek·div in·stə′bil·əd·ē]
(meteorology)
The state of an unsaturated layer or column of air in the atmosphere whose wet-bulb potential temperature (or equivalent potential temperature) decreases with elevation. Also known as potential instability.

convective instability

convective instabilityclick for a larger image
A parcel of air is stable at A and B and becomes unstable at C indicating convective instability from C onwards.
The state of the atmosphere in which there is a high relative humidity at low levels and a low relative humidity at upper levels, such that if a low layer of air is lifted bodily, the ELR (environmental lapse rate) value through the layer will gradually increase until it attains an unstable value. ELR is the lapse rate in the surrounding air within which a volume of air is being lifted. DALR, or dry adiabatic lapse rate, and SALR, or saturated adiabatic lapse rate, are lapse rates of dry and saturated air masses, respectively, when they are lifted adiabatically. The values of DALR and SALR are 3°C and 1.5°C/1000 ft, respectively. This is often seen in cold fronts, where convective instability is the major cause of instability. Also known as potential instability.
References in periodicals archive ?
Therefore, NODA contains information only on larger-scale convective instability but not on individual convective cells, which are typically resolved at O(1)-km grid spacing or smaller.
3) We explain below two important processes to understand interaction between gravity waves and background mean zonal winds, the critical level interaction and convective instability.
It is theoretically predicted that the instability of a gravity wave can be attributed mainly to convective instability for the high frequency components of gravity waves, and to shear instability for the low frequency components.
Convective instability ensues, producing turbulence as shown in Fig.
1973), Convective instability in the thermal entrance region of a horizontal parallel plate channel heated from below, J.
MOLNAR, (1981), Convective instability of a thickened boundary layer and its relevance for the thermal evolution of continental belts, J.
KELEMEN (2001), On the conditions for lower crustal convective instability, J.
Examples include his insights on magnetic island healing, curvature effects on island evolution, and convective instability of drift waves.
These products are designed to assist in identifying areas of increasing convective instability, pre-radar echo cumulus cloud growth preceding thunderstorm formation, storm updraft intensity, and potential storm severity derived from lightning trends.
e] differences are then computed from the gridded forecast parameters to provide an objective means of identifying where convective instability is expected to change in the next 9 h.
Here, propagating cold pools provide the necessary kick for releasing convective instability, leading to cloud growth and precipitation and further propagation.
However, orographic precipitation associated with conditional convective instability is very sensitive to a number of factors related to cloud microphysical processes and to the complexity of the orography itself (Miglietta and Rotunno 2009, 2010).