What is thermal stratification?

Thermal stratification refers to the phenomenon where layers of fluid, typically water, form distinct layers based on temperature differences. In this process, warmer, less dense water tends to rise to the surface, while cooler, denser water sinks. This layering effect can lead to variations in characteristics like temperature and density throughout a body of water, such as in lakes or oceans. Essentially, thermal stratification is a consequence of the fact that temperature influences the density of fluids, leading to a stable structure where the hot and cold layers remain separate unless acted upon by external forces like wind or turbulence.

While mixing of fluid layers is a related concept, it does not accurately describe thermal stratification, which focuses specifically on the establishment of thermal layers rather than their mixing. Evaporation and freezing involve phase changes of water and do not directly pertain to the layering caused by temperature differences. Thus, the correct understanding of thermal stratification is indeed about how fluids can be stratified based on their temperatures.