Isopycnic

[clarification needed] Isopycnic typically describes surfaces, not processes.

The term "isopycnic" is commonly encountered in the fluid dynamics of compressible fluids, such as in meteorology and geophysical fluid dynamics, astrophysics, or the fluid dynamics of explosions or high Mach number flows.It may also be applied to other situations where a continuous medium has smoothly varying density, such as in the case of an inhomogeneous colloidal suspension.

The term "isopycnic" is also encountered in biophysical chemistry, usually in reference to a process of separating particles, subcellular organelles, or other substances on the basis of their density.

After this gradient is formed particles move within the gradient to the position having a density matching their own (this is in fact an incorrect description of the exact physical process but does describe the result in a meaningful way).

In geology, isopycnic surfaces occur especially in connection with cratons which are very old geologic formations at the core of the continents, little affected by tectonic events.

Viruses purified by isopycnic centrifugation— a density gradient was formed during high speed centrifugation of a solution of caesium chloride and the two virus types come to rest at points corresponding to their density. The tube is about 10cm long.