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Stable stratification of fluids occurs when each layer is less dense than the one below it. Unstable stratification is when each layer is denser than the one below it. Buoyancy forces tend to preserve stable stratification; the higher layers float on the lower ones. In unstable stratification, on the other hand, buoyancy forces cause convection ...
Atmospheric instability is a condition where the Earth's atmosphere is considered to be unstable and as a result local weather is highly variable through distance and time. [ clarification needed ] [ 1 ] Atmospheric instability encourages vertical motion, which is directly correlated to different types of weather systems and their severity.
If the acceleration is back towards the initial position, the stratification is said to be stable and the parcel oscillates vertically. In this case, N 2 > 0 and the angular frequency of oscillation is given N. If the acceleration is away from the initial position (N 2 < 0), the stratification is unstable. In this case, overturning or ...
and are functions of the atmospheric stability class (i.e., a measure of the turbulence in the ambient atmosphere) and of the downwind distance to the receptor. The two most important variables affecting the degree of pollutant emission dispersion obtained are the height of the emission source point and the degree of atmospheric turbulence.
Most of the atmospheric heating is done by the Earth's surface as the atmosphere is transparent to solar radiation in most parts of the spectrum. [6] Considering only pure radiative equilibrium, the layer close to the surface heats strongly and becomes unstable. To balance this instability, atmospheric motions, like convective updrafts ...
CTDMPLUS – A complex terrain dispersion model (CTDM) plus algorithms for unstable situations (i.e., highly turbulent atmospheric conditions). It is a refined point source Gaussian air quality model for use in all stability conditions (i.e., all conditions of atmospheric turbulence) for complex terrain.
Verifying the existence of alternative stable states carries profound implications for ecosystem management. If stable states exist, gradual changes in environmental factors may have little effect on a system until a threshold is reached, at which point a catastrophic state shift may occur. Understanding the nature of these thresholds will help ...
A ball on the top of a hill is an unstable situation. In dynamical systems instability means that some of the outputs or internal states increase with time, without bounds. [1] Not all systems that are not stable are unstable; systems can also be marginally stable or exhibit limit cycle behavior.