Lämpötilakerrostuman

Lämpötilakerrostuma refers to the stratification of water in a body of water based on temperature. This phenomenon is particularly noticeable in lakes and the ocean, where distinct layers of water with different temperatures can form. The primary driver of this layering is the density of water, which varies with temperature. Colder water is generally denser than warmer water, causing it to sink.

During summer, in temperate regions, lakes often exhibit thermal stratification. The top layer, known as the epilimnion, is warmed by the sun and is relatively warm and less dense. Below this is a transition zone called the metalimnion, where the temperature decreases rapidly with depth. The deepest layer, the hypolimnion, remains cold and dense, as it is insulated from solar heating by the layers above. This stratification prevents significant mixing between the layers.

In autumn, as surface waters cool, the density differences decrease, and wind action can lead to mixing. This process, called overturn, mixes the entire water column, redistributing oxygen and nutrients. Winter stratification can occur if ice forms, with the coldest, densest water just above freezing point at the surface, and slightly warmer, denser water below. Spring overturn follows as the ice melts and surface waters warm to the temperature of maximum density, leading to mixing again.

Oceanic thermal stratification is more persistent and complex, influenced by salinity as well as temperature. The upper, sunlit layer is typically warmer and less dense, while deeper waters are colder and denser. This layering has significant implications for marine life, affecting nutrient availability, oxygen distribution, and the habitats of various species.