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Rarefaction is the reduction of an item's density, the opposite of compression. [1] Like compression, which can travel in waves ( sound waves , for instance), rarefaction waves also exist in nature. A common rarefaction wave is the area of low relative pressure following a shock wave (see picture).
In ecology, rarefaction is a technique to assess species richness from the results of sampling. Rarefaction allows the calculation of species richness for a given number of individual samples, based on the construction of so-called rarefaction curves. This curve is a plot of the number of species as a function of the number of samples.
He was the first recorded philosopher who provided a theory of change and supported it with observation. Using two contrary processes of rarefaction and condensation (thinning or thickening), he explains how air is part of a series of changes. Rarefied air becomes fire, condensed it becomes first wind, then cloud, water, earth, and stone in order.
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle . [ 1 ] It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within ...
If gas-dynamics is inverted, the opposite occurs, namely rarefaction shock waves are physically admissible and compressions occur through smooth isentropic processes. [24] As a consequence of the negative value of , two other peculiar phenomena can occur for BZT fluids: shock splitting and composite waves. Shock splitting occurs when an ...
As such it is the opposite of "condensation", "addensation", or "volume contraction". In sound waves the medium suffers rarefaction half of the time, but is under compression all the time. The opposite of compression in fluids is rarely observed since most fluids will boil (cavitate) before the pressure gets reaches zero.
Anaximenes held that air could change into other forms through either rarefaction or condensation. Condensation would make the air denser, turning it into wind, clouds, water, earth, and finally stone. Rarefaction would make the air less dense as it eventually becomes fire.
Nuclear mushroom clouds are often accompanied by short-lived vapour clouds, known variously as "Wilson clouds", condensation clouds, or vapor rings. The "negative phase" following the positive overpressure behind a shock front causes a sudden rarefaction of the surrounding medium. This low pressure region causes an adiabatic drop in temperature ...