Lämpötilastratifikaatio

Lämpötilastratifikaatio refers to the layering of water in a body of water, such as a lake or the ocean, based on temperature. This phenomenon is driven by the fact that water density varies with temperature. Colder water is generally denser than warmer water, causing it to sink.

In lakes, this stratification typically occurs during summer and winter. In summer, solar radiation heats the surface layers, creating a warm, less dense epilimnion. Below this lies a transitional zone called the thermocline, where the temperature drops rapidly. The deepest, coldest, and densest layer is known as the hypolimnion. This stratification prevents mixing between the layers, affecting oxygen distribution and nutrient cycling.

During autumn, surface waters cool, become denser, and sink. This leads to a mixing of the water column, a process called turnover, which redistributes oxygen and nutrients. In winter, ice formation on the surface insulates the water below, and the coldest water (just above freezing) is at the surface, with slightly warmer, denser water at the bottom. Spring turnover occurs again as the ice melts and the surface water warms and mixes with the deeper layers.

Oceanic temperature stratification is similar but often less pronounced due to factors like salinity, currents, and depth. The permanent thermocline in oceans plays a crucial role in global climate regulation and marine ecosystems. Understanding temperature stratification is vital for fisheries management, water quality assessment, and climate modeling.