Density gradient

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Density gradient is a variation in density over an area. The term is used in the natural sciences to describe varying density of matter, but can apply to any quantity whose density can be measured. ^{[1] [2]}

Contents 1 Aerodynamics 2 Water 3 Biology 4 Sociology 5 References

[edit] Aerodynamics

In the study of supersonic flight, Schlieren photography observes the density gradient of air as it interacts with aircraft. ^[3]

[edit] Water

A steep density gradient in a body of water can have the effect of trapping energy and preventing convection, such a gradient is employed in solar ponds. In the case of salt water, sharp gradients can lead to stratification of different concentrations of salinity. This is called a Halocline. ^[4]

[edit] Biology

In the life sciences, a special technique called density gradient separation is used for isolating and purifying cells, viruses and subcellular particles.^[5] Variations of this include Isopycnic centrifugation, Differential centrifugation, and Sucrose gradient centrifugation . A blood donation technique called Pheresis involves density gradient separation.

[edit] Sociology

In the study of population, the density gradient can refer to the change in density in an urban area from the center to the periphery. ^[6]

[edit] References

1. ^ Non-Destructive Testing Resource Center - Glossary.
2. ^ Chicago Wilderness Journal, Volume 1 - Number 1 - November, 2003.
3. ^ CFI-Shadowgraph/Schliren Photography for Aerodynamic Applications.
4. ^ Effects of sill processes and tidal forcing on exchange in eastern Long Island Sound.
5. ^ GE Healthcare Density Gradient Separation.
6. ^ The Spatial Distribution of Population in 48 World Cities: Implications for Economies in Transition.