Kylmäjako

Kylmäjako, also known as cold stratification, is a phenomenon that occurs in bodies of water, particularly in lakes and reservoirs, where the water temperature decreases with depth. This process is driven by the cooling of the water surface during winter, which causes the denser, colder water to sink to the bottom, while the warmer water remains at the surface. The result is a vertical temperature gradient, with the coldest water at the deepest point and the warmest water at the surface.

Cold stratification is a common feature in temperate and cold climates, where the water bodies experience significant seasonal temperature changes. It typically begins in the fall when the water surface cools, and the stratification becomes fully established by winter. The stratification can persist throughout the winter, with the water column remaining relatively stable.

During the spring, as the water surface warms, the stratification begins to break down. The warmer surface water mixes with the colder, deeper water, leading to a more uniform temperature throughout the water column. This process is crucial for the ecological health of the water body, as it ensures that the entire water column receives adequate oxygen and nutrients.

Cold stratification can have significant impacts on aquatic ecosystems. The stratified layers can limit the vertical mixing of nutrients and oxygen, which can affect the growth and distribution of aquatic plants and animals. Additionally, the cold, deep water can create a habitat for certain species, while the warmer surface water supports others. Understanding and monitoring cold stratification is essential for managing water bodies and maintaining their ecological balance.