Glossary
The English version of our glossary is currently under construction and will be regularly updated.
Density anomaly
A density anomaly is a phenomenon in which a given substance’s density does not change with temperature or pressure in a linear manner. Instead, the density peaks at a certain temperature and/or pressure before declining again.
The density anomaly phenomenon can be observed in various materials but is particularly associated with water (negative thermal expansion). Because of the density anomaly of water at ca. 4° C, ice has a lower density and floats, as it is less dense than liquid water. This also has substantial effects on the ecosystems of oceans and other water bodies, as it helps ensure that deep water bodies at high latitudes don’t freeze.